I also get the black circle with a V in the middle android Mull/Firefox

Honestly, it's probably just the way firefox handles PWAs. The overall experience on Firefox is not as good. Personally, I'm using edge. But when I tried Firefox a couple weeks ago with Voyager, it wasn't great. There was a whole thread about it, if I can find it I'll link it.

Edit: https://lemmy.world/post/1884607

I think it's because Firefox refuses to use TLS 1.3 to download the favicon for some weird reason. I won't support TLS 1.2 on vger.app, so using m.lemmy.world seems like a good workaround.

The main difference I see is Chromium based browsers install it to your app drawer like a regular app

I'm using Firefox for everything except Voyager for which I'm using Chrome.

I usw fenec from f-droid and it works Luke a charm

Another one that you can use is Kiwi Browser, it's exactly like Chrome, but it lets you install extensions, like uBlock Origin for example.

I use Firefox for Voyager, but I just assign a new icon to it. Works fine for me!