If you want software that gives you the four freedoms (to use, share, modify, and share modified copies) then blocking network access is orthogonal to that.

The free software movement is often misunderstood as being about privacy or internet access but it's really about control over your computing, being able to make your computer do what you want, and sharing your improvements with the community.

Although, the FUTO app itself is already proprietary and the Heliboard uses a proprietary blob for swipe typing.

That's what I'm wondering too... Gboard with no network permission seems pretty ideal.