You go self-hosted and try to stick to real small alternatives, subset of technical standards, etc.

I am not a US citizen, but a EU one (well, since we have seriously rogue and toxic EU states, I dunno how long it will last).

And guess what, the handling of the issue of technical interop for administration online services is done... at the top of the top of the political power: in my EU country, only the president and prime minister do define it. Yep, you read well, it is THAT MUCH important: parliament, no power over it, 'technical authorities' have actually no real power over anything, etc. It requires the same level of power than deciding to make more nukes.

Basically, in 2015/2016 our president/prime minister at that time literaly gave all the administration (and dependencies) online services to big tech (a technical document which is basically 'law' with a content 'opening the gate' for big tech). Well, I say 'they gave it', but they could have 'sold it'... we have a department in our DOJ to monitor past politicians who could have set up some public money channels in order to benefit from it, often indirectly, afterwards. The following president and prime ministers did change nothing... how deep the rabbit hole goes? Brain washing via hardcore lobbying? Corruption?

IRL, you had country administration related web sites, working more that fine with "any browsers", small and big, citizen made, small company made, now it is over, they were all broken for web apps which do work only with whatwg cartel web engines with their abomination of "computer language" requiring an even worse SDK. Same with file formats.

There is light though, if this document of technical 'law' is properly modified, the whole administration and dependencies have 3 years to restore simple web sites and support minimal and subset of file formats.