"Now consider what that means for software, a fully unregulated industry. It means some form of credentials…"
So what! Until the 20th Century pharmaceuticals/medicines were unregulated (eg: buy laudanum (opium) anywhere without regs and instructions said it was fine to give it to kids). After deaths, disasters and addiction regulations tightened—especially so after birth defects and thalidomide. Now the industry is tightly regulated.
Right, it took over one hundred years for pharma to be regulated. So be it for software. It's time the Wild West came to an end.
There'll always be whingers along the way, especially if they stand to lose profits. The "Good Times" for the software industry ought to be over because consumers are no longer benefiting in the way they should. Want a quintessential example of 'junk' software: Windows 11.
Existing regulations should cover software in their respective industries. Outside of that what you are asking for is simply onerous and isn't something that can be regulated in a meaningful manner.
We've already had opensource projects threatened by the age-check legality nonsense (which cannot be enforced). If you regulate what features can/can't be in an OS you will end up negatively affecting opensource and/or hobbyists which will give the consumer less choice.
The only reason we have an actual alternative to Windows is because people create their own Linux distros and software around it.