Android Question [SOLVED] Do I need an Android 7.x reference phone?

for testing u can use the device emulator, but emulators are not really the same as real hardware.
if u have a device with 7.x be aware that other manufacturer have a different modified os.
testing at least 4,5,6,7,8 os is very time expensive.
tablet and phone behave also different.

about 7.0 or 7.1
guess that 7 had bugs and 7.1 was the better version.
so a app can have trouble at 7 and at 7.1 it runs well.

from past every big change in number had a new surprise os manner.

An Android 8 device is currently a must. I don't see any real requirement for an Android 7 device.