Will the devices you provide or recommend be free of leaking through baseband?
The problem I’m referring to is described there: https://blog.wirelessmoves.com/2014/08/supl-reveals-my-identity-and-location-to-google.html
According to https://www.kuketz-blog.de/android-imsi-leaking-bei-gps-positionsbestimmung/ it would be possible to detect such a behaviour by using a tool called HackRF One.
I think you should take care of this problem in order to come as close as possible to your valuable goals.