Could Starlink terminals be used with Eutelsat?

I was reading that Ukraine has ~40 000 Starlink terminals, and switching to Eutelsat would take some time because of the availability of Eutelsat terminals.

I was wondering: would it theoretically be possible to flash a custom firmware on a Starlink terminal in order to make it work with Eutelsat? Or are there fundamental differences in hardware that would prevent that?

If technically possible, what would prevent Ukraine from doing it? I get that Eutelsat cannot openly do it, but what if some hacker somewhere managed to do it? Would it be a worthy solution?