TL;DR (From Android Authority)
• Mozilla responded to a review mentioning the lack of tablet UI optimization for Firefox on Android.
• Mozilla confirmed that its team is not working on optimizing the tablet experience at the moment.
• Mozilla did, however, say that it hopes to revisit tablet optimization when time and resources permit.
Interesting, how? Does Mozilla have an Android version of their full desktop browser?
Its the Linux version. You need to setup Termux with a Linux desktop for it to work. As I recall the ESR version was the only one that worked properly. This was 4 years ago now so it may not work.
Just a side note, if you do install Termux make sure you install it from F-droid. The Termux from the play store is missing functionality and tends to ddos the repos. It also isn’t really maintained.