The issue is that the standard is shit. I'd welcome some third party stepping up and dethroning Sonatype as the one and only gatekeeper of the whole Java/Maven/Kotlin/etc. ecosystem. I don't see what entitles them to that position other than some easily changed defaults in gradle and maven.
Especially, with kotlin multi platform, maven central is a PITA to setup. I gave up last time I tried it. And I really tried. Nothing I tried worked.
Pro tip: with gradle you can publish via ssh to a standard web host or to s3/gcloud buckets. Works out of the box without any special plugins. We have a simple bucket with our load balancer in front of that. Works great. You can do private and public repositories like this.
Sadly jitpack doesn't work for multiplatform builds and they seem a combination of too indifferent/unwilling to do anything about it. So, I can't recommend that. Jcenter is pretty much gone so that's a no go. Github repositories require logins. So that's useless.