Add HTML signature file in TBA

Greetings, Question 1: How can I add an HTML signature file for an account in Thunderbird for Android by referencing a file on my phone? Or, something similar that will accomplish the same thing (i.e., HTML email .sig). Background: In Thunderbird on my Desktop (currently using 140.10.1esr), I can go to Account Settings, select an email account, check the "Attach the signature from a file instead (text, HTML, or image):" and then "Choose..." a file I created on my local machine. My file is HTML (e.g., mysig.html) and references an image (in the same local directory). I want to replicate this in TBA. Question 2: If there is no way to do this (the functionality is not purposefully there and there is no work-around to fool TBA into behaving properly), is there a place I can submit this request to the developers? Thanks, Jarvis