> Semantics over the name aside, you end up returning small chunks of HTML from newly defined routes that are only useful for your HTMX frontend, hence my usage of API as the interface really only makes sense to the machine and not the user without the rest of the page content.

Web2py (being phased out by py4web which I haven't tried) made that very easy. If your api is accessed as api/hello.html, it can return HTML. According to the extension, hello.json, hello.csv, hello.txt, hello.pdf, etc. can return the adequate content.

Of course you can always return JSON regardless of the extension, but I found the same endpoints serving different formats very convenient.