In any future worth being a part of, OpenCore (OC) hides all the disruptive details of your kit from MacOS, so anywhere / any way you can get a complete install of Big Sur it can be meet your need for new kit.
The trick, as you are seeing, is the specific OC config for your kit.
Solving the problem of getting your existing hack to run Big Sur does not imply that config will work on your new kit. So you can't front-end load your effort. Each build is its own situation.
By getting Big Sur to run on your old kit, you gain experience and tools that can help with new build, and there are plenty of config situations that transcend or are independent of build, but the best place to address these is on threads that pertain to your specific kit at hand.
If you discover that a z390 gen config for X can carry over to z590 gen for Y with a basic formula, this information is helpful. But you almost never come across these stories because of the generational changes in architecture and macOS evolution over architecture.
So, while it's a good move to try to get ready, there's nothing about mac OS to make ready. Your specific build config is what needs the work. And for this you need access to your new kit
As to your old kit and learning tools / techniques, threads pertaining to a golden build of that same generation, or to specific configuration aspects are the right place to plumb it out.
When your new kit is in hand, there are a number of EFI submissions on this thread to choose from.
Or, get involved with the HackinDrom configuration database project. There you can find a config baseline to help you.
web.basemark.com
