There are dozens of alternatives like mithril - small in size, scope and community. You might miss a system for managing state in Mithril, as well as pre-built component libraries like Vuetify or react-bootstrap.
There are two different material design libraries for Svelte. [0][1] I wasn't able to get either of them to behave. It looked like they weren't being kept up to date with Svelte, or else the documentation was inadequate.
I then gave Angular a go, and encountered no such issues. Angular has the added bonus that its material design library [2] is very mature and well polished.
In terms of being in widespread use, I believe Angular is either #1 or #2 (competing against React). It's certainly not a 'cool' choice, it's a boring and stable choice, but there's a lot of value in that.
I use lit-html for rendering.
Then I sprinkle in components as I need from things like ionic or shoelace.style
Mithril is sorta unique in taking the more batteries included approach that angular and ember adopt, though it is admittedly far less kitchen-sink-ish
It's specially created for SPAs.