You can still play with all the legacy options. Some things will get tweaked slightly but we are moving copies of the renamed and reprinted items to a module, and while alignment will be vanishing from the sheets in a dedicated section it will stay accessible in actor data and the same module will make it show up in the actor traits (which, they probably should have been in there all along actually).
The remaster is not the giant change people seem to think it is, and we are trying to make it as seamless as possible for people while also not ballooning our compendium size to unmanageable levels or offering conflicting sets of legacy/remaster data and rules to people. We're treating the remaster as errata, and most groups will hardly notice the changeover.
If roll 20 works better for your group, great. Use the VTT that works best for your group. We'll keep working to make the PF2e system better, and trying our best to manage a fairly difficult situation data wise in a way that makes the most sense going forward.
Thank you for going deeper into this. I personally prefer Foundry - it does almost everything better than Roll20 (and the one or two things I prefer about Roll20 is probably a matter of me not finding the right modules yet). Plus Foundry does more, makes character creation a snap, and the production value of the AP adaptations are on a totally different level, allowing me to run a more cinematic game.
Your reply has me leaning back towards using Foundry for this adventure. My biggest concern is that I've got 2 university students with limited funds who just purchased the Core Rulebooks on my recommendation since we're planning to stick with the legacy rules and I don't want to invalidate their purchases. As long as the legacy system spells & feats etc are available, then we'd be fine.
One other thing that might might help - I accidentally upgraded to the most recent version of Foundry with the Rage of Elements upgrades included. When I tried looking up the...
Unfortunately if you put in the terms from the OGL into the product, then it can't be licensed under the ORC. To use anything from the OGL, you have to follow the OGL license and include it in your product, and it conflicts directly with the terms of the ORC. It's one or the other, you can't have both.