A control to scale the ui would be really useful. I use Lovelace and on some tablets it’s hard to fit the stuff you want. If I could set a scale for the ui that would be handy.
Individual item scaling would be useful too but even a basic global scale would solve most of the issues I’ve had with different screen sizes
Companion App (at least for iOS) has a “scaling” settings.
In general, adapting a web page to a particular client is not a trivial thing and should be solved individually.
As a possible method: define a custom theme with particular fonts/paddings/other sizes for a particular client, then set this theme on this client (ofc it may not solve all possible issues, just a possible way).