But for cellphones, lots of values of "niche audience" end up with, "pick zero." Here are some examples:
1. Hook up a keyboard to ssh into the device. 2. Hardware switch to turn off the baseband OS. 3. Software toggle to turn off the baseband OS. 4. Sandboxed baseband OS that isn't proof-of-concept or impossible to buy and use in the U.S. 5. Free software baseband OS. 6. Open source "tivo-ized" baseband OS. I.e., user can read the source but cannot run modified version. 7. Just glue together a damned RPI with a baseband OS and ship it to me in working order.
Those are just the niches that interest me. Only #8 looks feasible in the near future and its apparently still in the planning stage:
https://www.crowdsupply.com/arsenijs/zerophone
So I think your "niche audience" needs an asterisk that says, "most niches not yet supported."