Maybe I am not understanding completely what you are missing, but there is an SPA integration that gives you instant navigation. It also features pre-fetching, so it’s not limited to already visited pages.
Then what's the point? With NextJS I can have SSR but with client side navigation hydration. It's simply a better solution for that use case than an almost year old random library for Astro. Astro is good for traditional MPAs that don't need much interaction.
Sure, I wasn’t saying Astro is for every use case. Like, no tool ever is.
Indeed, hence why I said I moved back to NextJS for my use case, personally speaking.