There's a whole community of DIYers building e-foil boards at https://efoil.builders/. I haven't actually built one because I don't think I would ride it enough to justify the cost.

I do lurk on that forum and check out the projects people are making, there's a lot of really cool work done to 3d print propellers and other structural parts and bring the cost of manufacturing down. Between rapid prototyping and chinese BLDCs / ESCs, small electric vehicles like e-foils are actually reasonably priced to build yourself.