For what it's worth, ecosystem is a valid concern, esp compared to React, and esp if dealing with more niche features. Even for something fairly generic like Virtual List implementations. Virtual Lists do exist for solid (specifically tanstack is the most fully-featured, albeit under-documented), they aren't as battle-hardened or as well-documented as their react counterparts. Specifically, I have thought about digging into VirtualList internals, because of a couple issues that I haven't seen in some other framework impls (granted, of most the complex generic ui components, virtual-list is literally the one issue I had with ecosystem).
Also, you'll definitely start seeing edges faster. Things like touch event libraries, animation libraries, maplibre/dataviz/etc. I'd say that the solid ecosystem is at the point where you'll see 1-2 libraries for most things, but if those libraries aren't quite right for you, you can very quickly find yourself digging deeper than you'd like.
That being said, as parent stated, integrating vanilla libs isn't so hard. And also, there is a... solid... amount of people building headless libraries specifically for the ecosystem, which are quite useful (For example, I recently came across https://corvu.dev, which I've started integrating here and there). What I mean to say is less that solid has a poor ecosystem, and more that there isn't the infinite easy-access vibe-code-able pop-in-lib-to-solve-your-problem ecosystem of react.
Even with the shallow ecosystem, solidjs has been quite enjoyable to me. Also, in the two years I've been using it, I think I've built up enough of my own personal ecosystem that I don't really need to reach towards external dependencies all that much, which feels very nice.