@djsumdog FUTO software uses a disgustingly proprietary license that denies all 4 freedoms; https://lab.vern.cc/gitlab.futo.org/keyboard/voiceinput/-/blob/master/LICENSE.md (link that works without proprietary JavaScript).

https://www.gnu.org/philosophy/free-sw.en.html#four-freedoms
>You may use or modify the software only for non-commercial purpose
Denies the freedom to run the program as you wish, for any purpose (freedom 0) & denies the freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.

>You may distribute the software or provide it to others only if you do so free of charge for non-commercial purposes.
Denies the freedom to redistribute copies so you can help others (freedom 2) & denies the freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

https://www.gnu.org/philosophy/free-sw.en.html#selling


You appear to have assumed that "FOSS" means; gratis, source-available (proprietary) software, which FUTO software is.

"FOSS" attempts to be neutral between the freedom of free software and the corporate boot licking of "open source", but as you can see, it spectacularily fails at even that; https://www.gnu.org/philosophy/floss-and-foss.html

>There are FOSS solutions for going the other way around (text to speech) like Piper: https://github.com/rhasspy/piper
Piper is proprietary software, as the result of the training data is software and that software doesn't have source code.

There is free software TTS's available like espeak-ng

>or maybe I should try porting FUTO
Please do not port more proprietary software to the GNU/Linux-libre OS, which is meant to be a 100% free software OS that respects the users freedom and every proprietary program added is yet another step away from that goal.