Yeah, Lit is cool & futuristic. However, it's built for ES2019. It requires some effort to make it compatible with previous browsers: https://lit.dev/docs/tools/requirements/
In my opinion, this is the future. Especially, Native Web Components will take over in this decade. CalDOM's long-term plan is to seamlessly merge with native web components when it's widely supported.
Your reply encouraged me to experiment a little bit.
Turns out, CalDOM already seamlessly merge with native Web Components. I just didn't see it previously. :(
It can be used to create reactive, stateful & native Web Components. Check out this example: https://caldom.org/#web-components
If you happen to play with it, please let me know your suggestions to improve it.
Thanks!