It's really not that rare. Especially with stuff like ForeFlight.
https://download.aopa.org/advocacy/2019/dhowell_jking_DASC20...
> A majority of respondents had used ADS-B In, with 56% of respondents reported having experience with either an installed or portable system. Of the group who had experience with ADS-B In, 85% used portable systems and 30% used installed systems.
And that's in 2019.