A modern programming language that makes developers happier.

kotlinlang

I have a different perspective. Compose Web and Fritz2 may offer similar functionality. But Compose Web has a much, much bigger community behind it, and that really matters. I've enjoyed working with Fritz2, but I've found it incredibly frustrating to find zero training videos, zero libraries that can be used directly, and a two-week to two-month turnaround when I ask a question in this forum. By contrast, when I started to look at Kotlin Multiplatform, I immediately found five excellent videos that are teaching me how to build working multiplatform projects, including web -- no WASM required. And when I ask a question of an instructor on Udemy, he gets back to me in 24 hours.

Yes, but Compose Web is marked as experimental - is that reasonable to choose it for a new project?

I would.  They've got many good reasons to keep developing it.