They've not been mentioned/cast at all unfortunately AFAIK. Not mentioned in the revealed casts at all:
If you check these messages from Oda here, he mentions some deliberate changes/differences from the manga and implies some characters might be missing from this version. At least so far anyway:
We already seeing a bit of a shakeup with how Arlong is written and revealed in the story, playing a more overarching role, but I think the writer of this series said something about making Arlong play that role before, although I'd have to fact check that.
I heard Season 2 is already in the planning and maybe they're just saving Smoker and Tashigi for that too, as we should get Alabasta in Season 2? And thus Smoker and Tashigi there too? Otherwise idk tbh, it doesn't feel right to not have them at all in this so far. I mean Tashigi reappeared in the manga after YEARS and yet got to do nothing and no screentime anyway, Smoker is still AWOL/missing as hell for YEARS now too! Tashigi got a small update at beginning of Egghead or so but Smoker has not been seen since Punk Hazard IIRC!?
WTF is Oda doing with them?!