Can I implement my own plugin?

[Coro]

@RamSet

I don't think there is a (direct and ) easy way that a browser extension (or anything external for that matter) to add a link to the database.

I've seen only yesterday

https://github.com/pi-hole/AdminLTE/pull/1387

Isn't this what is looking for?

pi.hole/admin/api.php?list=white&add=dangerousstuff.com

@Bucking_Horn

You should be aware that Pi-hole is strictly a server. It doesn't require your clients to install any software, so there are no Pi-hole components running on a client.

I very much agree on this point. If there is a browser plugin available, users will install it without thinking about if they need it at all. They may even switch to using your plugin exclusively. Humans are lazy as you all know. If they can do something with one click less, they will adopt it. However, if something breaks, they will flood the Pi-hole forums with support requests even when nothing can be done about it here.