Can you elaborate on what you mean by this? Front-end framework don't care what language back-end logic is written in. For example, I have a Vue/Vite site that calls back-end functions that I'm gradually migrating from one language to another, and no front-end changes have been required.
There's also WASM, which is slowly gaining steam, but it still isn't a first class citizen like JS is.
You can also do the same in Node if you want to, I currently have a TS website that is mostly templated HTML in production (without htmx). Htmx would be perfect for that site.
Ah, so "with htmx you can use any language" is true because its users are no longer using a programming language per se for the front-end, but instead are defining logic with htmx's DSL?