I installed this on Firefox Nightly on Android, using a custom addon collection, to test the functionality. (I will never forgive Mozilla for killing the mobile extension ecosystem.)
It mostly works. Visiting a page without a tag causes one to be added, but with a small time delay.
Yes, I am aware of that, because of the way to validate if the meta viewport tag already exists by using the for loop.
I did it for backward compatibility, but since the most deprecated version in use of Firefox mobile is 68.11.0 (I guess), I'll replace it with the querySelector method.
