Can not install certain plugins due to UA

Pinephone with PMOS edge and SXMO.

I tried to install this plugin: https://addons.mozilla.org/en-US/firefox/addon/i-dont-care-about-cookies/ Firefox would not let me install the plugin, the page claims that the plugin does not supported Android. Indeed the UA is set to Firefox on Android. Just clearing the UA-override does not help as the page then thinks that the browser is not Firefox at all.

Sure, the root of the problem is that the plugin-page disables functionality based on sniffed UA, but still, it would be nice if we could just install plugins without mucking about. Is there a way to set the UA for the plugin page specifically?