This looks interesting for making SPAs and more app-like things, but then I haven't found things like Nuxt to be inflexible for that (never actually created a SPA with it though, just attempted to use it as an SSG).

Doesn't look like it would work for me though for the same reasons Nuxt doesn't. It's not really lock-in pain that's my problem btw, but more config fatigue and missing features, and if the SSG has a plugin system to counteract this, then there's the problem that most don't work well or age quickly (imo this is usually because the plugin system is not strict enough), and regardless of whether they work, you end up with this patchwork of plugins, with a bunch of hacks and glue code to make them interact nicely, it's awful.