Thank you, I'll be sure to look at these and add them in the Acknowledgements
Unless you drew inspiration from them (I'm assuming no, since you just heard about them), "Acknowledgements" doesn't seem right.
"Similar Projects" would be more accurate.
https://github.com/alpinejs/alpine (acknowledged in their readme)
https://github.com/stimulusjs/stimulus
https://github.com/intercoolerjs/intercooler-js
https://github.com/mavoweb/mavo
https://github.com/bigskysoftware/htmx
https://github.com/unpoly/unpoly
(ordered by GitHub stars)