Turbo stimulus and Strada..
HTMX... Nothing. Just serve it however you feel. In the posts case, they decided to add some tight coupling with go, while not for everyone, is not really a framework.
I appreciate go server for really lightweight banal sites or even light services and htmlx is quickly becoming my new favourite markup. I will say this project isn't for me, but casting it as just another 'fasthtml' project is a bit far off the mark.