User-Agent Switcher is just great and exactly what I was looking for.
It does exactly what the name suggests, it also works on Firefox for Android and it is Free Software (GPLv3). Also, I appreciate the extensive description.

great add-ons

Best addon for mobile version. I use it for "Always desktop mode" option

Very good addon, works great most of the time. Do you think you could add more mobile options like Windows Phone or LineageOS?

Hi,love it however feature request for keyboard shortcut to change the string manually while still preserving random mode, sorry dont have a gitlab account

Firefox for Android does not have an option to always show PC version in the settings, but this add-on allows you to always show PC version, which is very useful for tablet.

really helps me with work

Works perfectly. I can access subscription based forums with this :D

Jaj cool

Lo use para que el navegador de mi tableta muestre las páginas como un navegador de escritorio. Asi provecho mejor la pantalla, y tengo todas las funciones de escritorio

Used this add-on in order to be able to download the Office 365 installer from Microsoft their site. Without the Windows user agent the download/install button would not show...

Tried installing it in firefox nightly on android, following the linked instructions. Can confirm it works! (But yes its quite a few weird steps to take) Thanks! ♥