Coincidence? I think not.
This argument looks a bit silly when even the most cursory research would reveal that many major and widely-used open source projects are most significantly contributed to by people working for these "closed source tech giants".
a commenter with more patience than i have has posted a longer explanation at https://news.ycombinator.com/item?id=40835750 which i don't wholly endorse but which you'd probably benefit from reading
(as another commenter points out, futo's license is particularly broadly written, adding additional problems on top of the usual 'free for noncommercial use' problems)
> You may use or modify the software only for non-commercial purposes such as personal use for research, experiment, and testing for the benefit of public knowledge, personal study, private entertainment, hobby projects, amateur pursuits, or religious observance, all without any anticipated commercial application
https://gitlab.futo.org/keyboard/latinime/-/blob/master/LICE...
That reads to me that if I type a work email using this keyboard, that would be a commercial use and against the license which makes this a total non-starter.