I tested the app on BV9800 from Blackview a rugged smartphone. It runs perfectly on the device.
For that very reason I wish you would simply allow the PlayStore download for this device. No need for dedicated support and this goes for many other phones too.

Please consider to allow download for people just to try if it is working and be good with it instead of blocking them out.

People get apks and this is very insecure. Please allow a secure download over the PlayStore.