You probably still want to use a dependency manager (npm, yarn, etc) to pull in and own host your own dependencies. You don't want to pull your dependencies from an external source as that will only ever make your site less reliable.

> use es modules to handle splitting and caching the various .js files of my app

Yeah, I was surprised at how well es modules just worked when i put together this tiny repro https://idb-perf-repro.netlify.app/ (index.js imports two relative files)

> use this import maps feature so that i can [...] add the digest of the file to the filename

So you've still got build tooling and a layer of indirection. Maybe this is simpler, but you'll still need tooling to manage hashing files + creating import maps. I don't think import maps really gives you anything here, because if you're renaming all your files on deploy you may as well just update the imports as well, rather than using import map.

> Optimal file transfer - all in one js bundle, but if i have http2 then i don’t care because the overhead of multiple files is gone

This is the key part you would need to validate. Does HTTP2 really remove all overhead from requesting 100s of files vs 1 large file? I don't think this is the case.

> but i think i’d like simplifying my tool chain more and using something like htmx instead.

Simplifying your toolchain by removing type safety from your views.