I gone through a lot of hosting service providers and unfortunetly cannot find a single one that can be used without running nonfree programs, all of them require loading bulky obfuscated JavaScript apps.
I know of Codeberg Pages for static sites for example, but it is not suitable for any business or professional use.
You can use Ansible to create domain names and register URLs on most popular hosting providers/registrars.
You shouldn't avoid platforms just because they have non-free websites, that's extreme bro.
Eventually I can use those sites, but I am curious is there is at least one provider that does not require running their code on my computer and just send me the HTML (actual site).
No reputable registrar requires you to run an executable on your machine. JavaScript is as far as it'll get.
I'm sure many registrars work without JS, but if I had to be sure of any one in particular, it'd be Njalla. They even have an onion site and accept monero, so they almost certainly function without JS.
If you want extremely low overhead you can use the API directly with curl. Most hosting providers/registrars allow this.
I don't think you know what you mean/want. I never had any registrar requiring me to install anything to have my domain registered with them. The same is true about hosters too.
You didn't, but your browser was even if it doesn't tell you.