Wouldn't this particular example be better served through C++2a concepts? That is we can specify constraints about template type parameters.
I'll get back to you when my work projects are allowed to use a C++ version newer than C++11. </rant>
But, more seriously: I'm curious if so few people are actually using C++20 (for work, at least) that it will take a while to answer questions like yours.
In many business, many coders learn just enough to get the job done and never care about moving forward with their knowledge unless obliged to do so.
When doing contracting where one gets to jump into random codebases just for a couple of months, it is quite sadding the quality of code that we routinely find out.
It is like playing Mikado with code.
With C++ you're basically always at a point where you only know a little, even if you've worked on your C++ skills for years... :-P
Bare bones strcpy() and memcpy(), pointer arithmetic all over the place without helper functions to validate application invariants, #ifdef spaghetti code, not using translation units as poor man's modules,...