Posting in the d2r Classic Ladder section would be for PC specific trades as far as I know - and of course there is no cross-play.
I think your best bet would be posting in the Switch trading section and specifying your needs are for classic.
Maybe a TA or TM could confirm this for us :)
Thanks, this is what I figured but would be good to get a confirmation.
I have a follow-up question - do you know why d2jsp has a policy against cross-play? It's possible to transfer items PC<>console and vice versa, but based on my understanding this is against jsp's rules. I'm wondering if this is because of Nintendo/Blizzard's TOS or if jsp has it's own policy against it.