I would guess a swappable battery would be separated from the vehicle, similar to a gas bottle for a grill.
The battery would be rented for a small deposit and on swapping you only pay the energy + service fee.
I guess you could also buy one to own, but then could not swap that.
That’s how it would make sense, at least.
A fuel cell does not mean it’s an ICE. It will still use an electric motor and probably even a small battery.
Hydrogen ICE exist, but are more complex and less efficient.
You could use Hydrogen to produce so-called e-fuels (we had a huge debate about them in Germany), but those can typically be used in normal ICE vehicels.