For in-person workshops I'm a big fan of sticky notes. So it's pretty obvious that I'm a big fan of digital whiteboard tools. I highly recommend you use those for your next remote workshop.

My tool of choice and that has worked the best for me with many participants is Miro. It's a bit on the expensive side, but their consultant plan lets you run workshops with guest visitors without going bankrupt.

I curate a list of digital whiteboard tools here if you want to see other alternatives to Miro. By the way, if you like Miro, I have a few courses and templates for this specific tool that you can find in my Miro Bundle.