most people will use the word "thread" or the 🧵 when starting a thread, so this will work for many topics. Search for:

"thread" OR "thread:" OR "🧵" AND "[SUBJECT]"

e.g.
"thread" OR "thread:" OR "🧵" AND "tech"

but it will miss any that leave out the above keywords, so it's quite rough

I'm going through this at the moment. I'm playing around in Figma, and if I come up with something decent I'll stick with it. I want to get better with Figma anyway. If it turns out to be rubbish, then I'll probably try 99Designs.