Find and Replace does not recognize a regular space from a non-breaking space. If you search for non-breaking space, you will find both. If you try to replace something with non-breaking space, you insert a regular space only.
Find and Replace recognize the difference between a regular space and a non-breaking space. You will find or replace only the type of space you need.
The user could quickly replace or insert non-breaking spaces between a value and a unit. For example “80 kg”, “180 cm”, etc.
Ideally, this feature should be extended to as many whitespace characters as possible that can be implemented with a reasonable effort.