Connect is great, because you can use it to block posts with certain keywords automatically.

Besides that, wefwef.app is my favorite. You can really tell, that the devs there put a lot of passion into this.

would be great if Fdroid could support payments as well

If the extension you want to install is also on github, you oftentimes also get some easy instructions on how to install the necessary collection for this extension.

Still not very usable for casual users. I think on F-Droid there are some fairly uptodate Firefox forks with all extensions unlocked

I guess it is just not a popular feature on mobile. Most smartphone users don’t even know what a browser is, so ensuring addon support seems to be very low priority for Mozilla. Even a switch hidden somewhere in the about:config page in Firefix Nightly would be enough. These extension collections are the most user-hostile way of extension support possible. I just switched to Kiwi because of that mainly.

I think there are some Firefox forks with the entire extension store enabled, but I have not looked into this.

Kiwi Next has more frequent updates, last time I checked

Firefox or Kiwi. These are your options for extensions