Agree, that a board designed for two things, suck at both....
That was the reason why bidis/mutants died IMO
On the other hand, you have to learn both hydrofoiling and wavesurfing from the start I can understand, so the board actually does not matter much, as you can hardly feel what is good and bad, before after years - and then you will have changed boards many times.
Sounds pretty hard, but I am serious
What do you mean by "Would it be a problem to transition to strapless with this board?"
Are you talking about hydrofoil strapless, or waveriding ?
I would start strapless for waveriding, as if you have no experience you have to learn the board and edges inside out, and how "such a thing" works.
Then you can add straps later, when riding waves and you know how to now (or not if you prefer strapless, you will find out...)
For hydrofoiling, it works great strapless (a surfboard), and easy to make the transition (you have to start with straps, absolutely no discussion IMO).
So just the opposite here - start with straps for learning (it is the start that wont work strapless), and when you CAN hydrofoil, you can remove the straps and learn how to start, and enjoy riding freely on a silent flying magic carpet