Adding to this issue I would like to give some of my opinion on webext.

To be honest Firefox add-ons process is so grotesque. For instance I can't load my extension without signing in Firefox stable version. And their tool especially web-ext has lot of issues like takes lot of time, gives pesky error if your system time is incorrect (my isp has blocked ntp servers and idk why and switching to vpn just to update is painful tbh). And developing addon is also hard for firefox compared to chrome as the dev tools frequently give message unrelated to extension etc.

Sometime I get so angry but I have been using firefox nearly for decades. Its so hard for me :(

I want to give mine too, because I really appreciate how well it works for me. I built a Chrome extension and it runs fine on Firefox with 0 changes since Firefox supports the exact same browser APIs. When I was developing with Chrome, I had to manually upload my extension each time I updated it. web-ext reloads the browser for me automatically - you do have to take care to avoid duplicating the DOM since it doesn't reload the tab. Not sure why system time is so critical but it seems like a reasonable expectation.

I mean, the browser apis are close (and Mozilla still has much better documentation) but there are a LOT of edges cases where behavior diverges.

Frankly - I'm a little peeved that Optional permissions in Firefox are STILL broken - The prompt can only be triggered in response to a user action, and Firefox blows the fuck up if you put a promise anywhere in between the user click and the call to the api. Which is hugely ironic, since Mozilla is the one pushing to move all the webext APIs to be promise based (and provides a nice helpful library for Chrome/Edge/Safari support: https://github.com/mozilla/webextension-polyfill) which... doesn't work on their platform. Doubly ironic, since the result is that most FF extensions just ask for more permissions up front, which is exactly the opposite of what you'd want in the "secure/private" world Mozilla claims they're pushing towards.