htmx is only one of many different libraries & frameworks that take the hypermedia oriented approach to building web applications. I have said before that I think the ideas of htmx / hypermedia are more important than htmx as an implementation.
Unpoly is a wonderful, mature front end framework that has been used heavily (especially in the ruby community) for over a decade now. It offers best-in-class progressive enhancement and has many useful concepts such as layers and sophisticated form validation.
Datastar started life as a proposed rewrite of htmx in typescript and with modern tooling. It eventually became its own project and takes an SSE-oriented approach to hypermedia.
Speaking of Alpine (which is a common library to use in conjunction with htmx) you should look at Alpine AJAX, an Alpine plugin which integrates htmx-like concepts directly into Alpine.
Turbo is a component of the Hotwire set of web development technologies by 37Signals, of Ruby on Rails fame. It is a polished front end framework that is used heavily in the rails community, but can be used with other backend technologies as well.