Thats not going to be natively supported in my opinion.
You need to run alot of custom code in the form itself to get that done, so you’ll need javascript, I’m not sure if it even lets you run javascript like that because of security issues.
Maybe Apps can do it, but you will hit alot of roadblocks here.
I gave it a try, but as you mentioned, it’s quite complicated. It seems to require a lot of custom code, especially with JavaScript, and there are some security constraints that make it even trickier. Maybe Apps could handle it, but I think there would still be quite a few roadblocks along the way.
I appreciate your input, though! If you have any other ideas or workarounds, I’d be happy to explore them.
I’m not sure why you even want to do this to be honest? Perhaps you can explain why you need such functionality and the community can help brainstorm other solutions?
I can’t think of a need to do this in action center so I am curious.