Why are you looking at these units instead of normal domestic heat pumps?

Not much to add, other than to say that localised Fan Coils will have localised condensation plumbing associated with them, which you need to factor in a way of plumbing into your waste system. I'm working on a commercial project where the MEP strategy changed to FCU's and we now have lots of extra vertical pipe drops which weren't in the original design.

There's also a question of noise - MVHR's tend to be a centralised system in a utility room or loft space, moving air at fairly low fan speeds. The actual terminals are usually very quiet indeed (if the system has been designed properly). By contrast, I would guess that localised FCU's would be smaller and slightly noisier, but I might be wrong.

All that being said, there's some good info here about cooling with air and the limitations of this approach. It is always better to stop the heat from entering in the first place:
https://www.weare21degrees.co.uk/guides/maximizing-comfort-and-efficiency:-our-guide-to-mvhr-systems-and-cooling/

"The reason cooling isn’t very effective through the MVHR system is not down to the technology; it is down to the nature of air and heat/coolth. Air does not have a great heat/coolth carrying capacity, so if a space is to be cooled by air, an awful lot of air needs to be supplied to that space..."

Posted By: tonyThere can be problems with condensation on the outside of the cooled air ducts.

Good point. Thanks!