There's a few potential directions from which to answer this question:
This community is a fine place to discuss pathfinder 2e things. And in that respect at least it's similar to /r/Pathfinder2e.
Lemmy.ml is not a great instance that suggest new Lemmy users to create an account on, as it's gotten overloaded with the influx of new users and adding more accounts there is disproportionately likely to get the instance into performance problems. See https://lemmy.ml/post/1147770 for details. Instead recommend folks to pick an instance to join that currently has less than 500 monthly users from https://join-lemmy.org/instances.
No matter what instance someone joins, they can subscribe to this community which is homed on lemmy.ml, and federation will allow them to read and post comments on this community irrespective of what Lemmy instance they have an account on. Well, almost no matter what instance they choose. They should check lemmy.ml/instances/ to ensure the instance they're about to join is federated with Lemmy.ml, but almost all are.
The /r/Pathfinder2e mods haven't made any statements about the API changes or 3rd party apps. There's little chance of them supporting a mass migration of the whole community anytime soon (it's also not clear that the Lemmy ecosystem would gracefully handle that many people joining together). This is best thought of as an independent Pathfinder community that likely shares some people overlap with the subreddit (for now at least, I'm in both).
Maybe this gives you a few ways to think about your personal interaction here vs /r/Pathfinder2e, and ideas about what you'd want to suggest to friends or folks you like to chat about pf2e with.