Could feature XYZ which only affects a fraction of the user base be implemented?

In general, no, simply because resources have to be allocated primarily to features which impact the most users. If the team tries to implement everything, then it will take longer to deliver new functionalities and improvements.

The best thing to do when your feature has a low priority is to find people with the same needs and to create a team which can tackle the problem or sponsor the development (and maintenance) of the feature.