I've not used it in a team environment. I'm used to working with an FE developer or team. The last time I did js, jquery was the new hotness. For me on a personal project, I tried react and svelte. Both we monsters for building a site that needed some js elements and interaction. I was able to get htmx working quickly and I've only had a couple of snags.
One neat benefit is that I am now able to unit test (well, unit integration) my views with a headless browser because my UI is served by my backend and not a separate service that has to run with all the yarn and npm bs.
TL;DR: I'm a backend person who struggled to pick up react over a weekend but picked up htmx in an hour. Your FE devs will have no problems with htmx.
They will have to become familiar with your system's templates syntax and how to work in the backend to organize their partials and components and may even have to decide how that should all be structured.
One neat benefit is that I am now able to unit test (well, unit integration) my views with a headless browser because my UI is served by my backend and not a separate service that has to run with all the yarn and npm bs.
TL;DR: I'm a backend person who struggled to pick up react over a weekend but picked up htmx in an hour. Your FE devs will have no problems with htmx.
They will have to become familiar with your system's templates syntax and how to work in the backend to organize their partials and components and may even have to decide how that should all be structured.