Can I change or add a specific character to the keyboard myself?

So, last week I bought Thumb-Key on Google Play (without much research ... my fault). I saw some pictures and took for granted some features that are essential for me (a MessagEase user for almost 10 years). I actually enjoyed the feeling of Thumb-Key even more than MessagEase, but ...

I want to know if there is a way to have my specific keyboard (Portuguese), which is a variation of a Spanish keyboard with some accented letters and punctuations marks in different places (and floating diacritics, which is not a feature yet, right. I miss that, but it's not essential). I'd say that if I can get my letters in their correct places, it would already be usable, while I wait for the app to be more mature.

I read about the pull request procedure, but this makes an "official" language keyboard, doesn't it? As I understood it's not something that anyone can make, change a little something and have their keyboard there, or is it? Is there some procedure that I can make without being a seasoned programmer or customization is totally out of question? Is it fine if I make my idiosyncratic changes to ESMessagEase.kt, make it a custom PTMessagEase.kt and find my way in Github?

No. But you can add a new keyboard layout with the change and submit a PR.

See tickets

604, very similar to your request; and 586, a more general and better solution. Both have been rejected by @dessalines, and the ticket comments contain his thoughts on why not.