If the series turns into a long runner, the approach I would take is
Season 1- East Blue
Season 2- Laboon, Little Garden, Drum and Alabasta (that's all about 100 chapters, same as East Blue)
Season 3- Water 7. No Skypeia, no Foxy, no long ring.
Season 4- Thriller Bark, Sabondy with SOME Supernovas, Fishman Island, into the new world
Season 5 and 6- Big Mom, Kaidou, Shanks.
Season 7- Laugh Tale and War
I know some of you are looking at it and going "there seem to be some big parts missing..." well, yeah. If the show is a super huge mega Game of Thrones success, and if it was on HBO instead of Netflix, sky is the limit. But considering the huge pain Sandman went through to get renewed for a second season, and its a much less expensive show...
You HAVE to do Drum. It's one of the best most tear jerking stories Oda did, there's a reason they amde it one of the theatrical movies, it already fits into 2 hours cleanly, and you can get big celebrity Jamie Lee Curtis playing Kureha and advertise the shit out of that.
-Skypeia is too long of a detour away from what people will consider the main plot, (but you could plop it in as 3 or 4 episodes almost anywhere without disturbing the flow , just don't make it a full season... obviously that drastically changes the scope of what we know it as)
-Dreserossa is basically a more convoluted repeat of Alabasta so leave that out and just have Dofla as an endboss.
-Thriller Bark is still there as a QUICK fun change of pace. But you probably can't do justice with a giant Oars fight, so don't even try. No Nami being assaulted in the shower either. But badass moment for Usopp against Perona, entire crew works to fight moria, and Brook's flashback. Can probably do it in 2 if you cut out the various shadows being stolen or things like the General Zombies that ammounted to nothing.
-Same thing with Punk Hazard. No giant smoke death cloud that doesn't actually kill unless its only chasing everyone for like 10 minutes.
-Amazon Lilly could be... problematic with all the half naked women. The show suddenly turning into an epsode of Xena might be good for it, or considered offputting and pandering. Unless its just a single episode, and hey it was a short arc so it could be. but... depends on the costuming I guess.
-No Zou because unless they do something miraculous with Chopper, budgeting for all those animal people is just not going to work. Dark Materials could barely do animals and that was their main CG expense.
The biggest cut is... Everything about rescuing Ace in the war. Live action actors don't need an aging up timeskip , We don't need a full season of the ust-assembled crew scattered to the wind. You don't want an expesnve, giant, all-characters war with zero resolutions in the middle of the series, you save that for the end. You definitely don't need the Impel Down detour.
You either DRASTICALLY change all that so that it doesn't even resemble the manga at all anyway, or you skip it. That's a big 3 year, 2 season section you can just cut. If you want to have dramatic Ace death in the middle to shock audiences and get them talking, you can absolutely still do that, but you don't need a huge season long side arc mega-war dedicated to it.. just have Blackbeard kill him straight up. Or merge the Robin rescue with an Impel Down raid and take the crew with instead of of gathering up all the old villains. That would keep even us old fans on our toes.
Other time savers?
-No replacing Warlords. Once they're beaten, its done, the checklist is lowered. You start with seven, you end with three or four, you don't keep restocking them. No Buggy, Blackbeard, Law, Weevil filling the ranks, it just diminishes as it goes. (Wheel of Time needs to do the same thing, actually) If you want to do ONE replacement for Crocodile to bring in Blackbeard that's fine,
Same with Emperors. Don't declare Luffy an Emperor at all. Just let there be five of them when BB rises up, and have Whitebeard die in the final war instead of the midpoint.
Other benefit of doing that? You get to the Supernovas sooner. I would say for streamlinng just cut them entirely, but... Law is a thing. I don't care about Law at all but he's the series' Vegeta and consistently one of the top 5 characters, so you want to get him in as soon as possible. Hell, throw him into Alabasta if you want.
Don't introduce ALL of them, just the super popular ones, Law, Kidd, Bonney for a token female, and maybe one other... but you don't need to introduce 8 of them and promise future developments on all of them unless you're really gonna fodderize them.
Now if the series is a bonafide mega hit and everyone is enthused and they immediately get renewed and budgeted for multiple seasons, then maybe you can plan on doing a version of the war and Whitebeard's fall.... but scattering the crew for more than a few episodes is a no-no, and you really do want to save all that buildup for the finale instead of repeating yourself. Everythign cool and important that happened there can still happen at the end.
Any arc in the manga that took 2 years, think of the most streamlined clean version of that which would fit into 3 or 4 episodes instead of 80. Think of the sets that would be needed, how many actors hired, how any costumes, just what would be needed to do it any sort of justice... and what a super streamlined version might be like. If the streamlined version would just be a super pale shadow of it, then maybe, just maybe it can be cut and important elements can go somewhere else
We'll really get a taste of how that works depending on how they handle the Arlong arc, which was the first long arc in the series at 27 chapters/14 episodes, but they're only giving it 2 episodes live action. So it'll be a good signifier for what streamline plot and sped up fight scenes will do to the general pacing.