So for a React developer who doesn't want to include Shadcn/Radix, but also doesn't have time to build every component/a11y/compat/edge cases from scratch, what are the better alternatives?

Would be nice to list them here so developers can know a midpoint between DIY <-> Shadcn/Radix

One midpoint is traditional css frameworks like https://getbootstrap.com/.

Not as powerful, and you don't get this sweet 3rd-party pluggable component catalog, but it's much simpler and it's stable: there's no constantly evolving ecosystem.

Shadcn ecosystem might have calmed down by now, but when I used it years ago, the layers on top of it were super unstable, and I was annoyed every time I have to work on those projects until I got Opus 4.5 to refactor out of them.

There are many options, each with their own pros and cons. Also, you may or may not like their default styling and/or styling options. There is no one size fits all. Having said that, we maintain an incomplete list of popular UI libraries here:

https://frontaid.ch/web/ui/libraries.html

You don't want to build your own components but you also don't want to use pre-made components? At some point you have to pick one. If you really want a midpoint, it's literally Radix: behaviours are done, stylings are up to you

just discovered this link: https://designsystems.surf/design-systems

Claude Code can whip this stuff together quickly if you specify those constraints and are knowledgeable enough to know what’s possible with modern CSS, etc.