Except for the random choosing of instances it's easy to do with Redirector:

https://chrome.google.com/webstore/detail/redirector/ocgpenf...

https://addons.mozilla.org/en-US/firefox/addon/redirector/

Userscripts don't work too well for this, because you have to either check all links everywhere or delay redirection to only after you reached the page.

I use Privacy Redirect: https://addons.mozilla.org/en-US/firefox/addon/privacy-redir... It also works for Invidious and Bibliogram, but I only use it for Nitter.

There was also this from the other day.

LibRedirect: Redirect YouTube, Twitter, Instagram to privacy friendly services

https://news.ycombinator.com/item?id=32916318

I prefer bookmarklets for a few reasons:

Compatibility: Bookmarklets work on all devices. Deskop, iOS and Android.

Security: I can easily read and understand the code. They only run when I invoke them. While extensions have access to everything you do an any page, bookmarklets only have access to the page where you invoke them.

Flexibility: They are easy to change. For example in this one, I will probably update the array of Nitter instances regularly.

Usability: I can organize them just like my other bookmarks.

Sharing: I can put the bookmark in just a line of text in a text file with an explanation. As I did here. No need to dabble with extension repositories of Firefox and Chrome, as you would have to with extensions. I don't even know how it would work for other browsers.

They are great for us developers who can vet every line. But extremely dangerous for non technical users.

I use "nitter redirect" for firefox.

I actually don't like it, I spend more time on twitter now

Tampermonkey scripts combine well with this kind of thing, IMO; I use bookmarklets for stuff I only want to happen on command (https://maya.land/bookmarklets/readable/) and Tampermonkey to automatically or conditionally invoke bits (https://maya.land/user-scripts/hypothesis/)

You can just use any of the twitter/website redirector browser plugins to forward https://twitter.com/[X] to https://farside.link/nitter/[X]