firefox/mozilla doesn't really make it easy (compared to chrome)
mozilla now requires "add-on signing" [0]; extensions now have to be "signed" (By mozilla) before you can permanently side-load your own private extension onto regular firefox. they also require you to use 2FA [1] when setting up a firefox.com account (which is required in order for you to upload extensions so they can be signed).
at least with chrome you can just enable 'developer mode' and drag and drop your own extensions and use it right away without having to deal with any of that.
mozilla now requires "add-on signing" [0]; extensions now have to be "signed" (By mozilla) before you can permanently side-load your own private extension onto regular firefox. they also require you to use 2FA [1] when setting up a firefox.com account (which is required in order for you to upload extensions so they can be signed).
at least with chrome you can just enable 'developer mode' and drag and drop your own extensions and use it right away without having to deal with any of that.
[0] https://blog.mozilla.org/addons/2020/03/10/support-for-exten...
[1] https://blog.mozilla.org/addons/2021/03/11/two-factor-authen...