How to backup while Switching from Catalina clover to opencore big sur?

I have a Catalina laptop running OK with clover but I feel like it's time to move on. I'm planning on installing big Sur on my machine but want to switch to opencore as well.

I have periodic time machine backups but they aren't from big sur. So, I think those backups neither won't work or will downgrade to Catalina back? Could you tell me what would happen in this scenario?

If time machine backups won't do the trick, could you tell me what should I do? Should I use another app?

I have so many development libraries setup and I don't want to deal with those any more. I also have many apps that I needed to configured for my own taste. So, going completely fresh is not something I would like to do. Specially for development libraries. I'm not even talking about pictures, finished and ongoing projects, documents and etc.

Thanks

Edit: I also can clean install opencore Catalina and then update my laptop big sur , if thats the proper way.