I’m using PWAs for Firefox but I have barely used it yet to be honest. And one needs to download an app for that besides the plugin to get it working.
Besides that I do recall that Linux Mint shipped (and maybe still ships) a tool to create Firefox PWAs with. I never really tried it tho and I’m not sure if it is available for other operating systems beside Mint.
But similar to you, I’m in somewhat of an experimental phase concerning Firefox PWAs