It's a concern but it has been getting better. Dead code elimination (DCE) in kotlin.js has improved in the last year as they rolled out support for the new IR compiler with 1.5 and 1.6. It's still not perfect, but it's getting there.

For what it is worth, we are using the Fritz2 framework, which is quite nice. That was definitely a bit of a bet a year ago but we've stuck with it and they are getting close to a 1.0 now. We might switch to compose web at some point but it looks a bit early for that right now. One plus point with Fritz2 is that it comes with a nice component library, support for themes, etc. So you can get up and running pretty quickly without spending a lot of time on custom component design.