Earlier quoted context omitted.
I'm using several original BCM2835 Raspberry Pis and Pi Zeros (original) to compile pkgsrc packages for NetBSD on earmv4 and earmv5 because the newer ARM CPUs won't run anything below earmv6. There are some instructions the newer CPUs don't support that'd need to be emulated. With a USB attached SSD, they're quite reliable and run for many months at a time, compiling non-stop with no issues.
Yeah anything older than the Pi 3 with armv7 is also more or less unusable in terms of OS deps, since there just aren't many package releases being maintained for v6 and below.
The OS is fully, 100% supported, so we're not even talking about that. See:
http://nycdn.netbsd.org/pub/arm/
The number of packages available is decent and is only improving: