878 I don't have one, but I have an N76. The Winno devices are reasonably well-made, and the basic functionality of the N series is similar. The N76 has an additional V segment, which makes it more portable. You can use it for APRS, SSTV, or even create your own network link (which requires a backup phone). Decoding CW signals and APRS data are all done manually. I used to have an N65 on my motorcycle, which was very stable. The phone's built-in frequency control is also quite reliable, and I've been using it with Bluetooth headphones for several years.
When using the SSTV app to receive images, the signal can be unstable and disconnect. It's better than the computer version, but at most it just shows a single line of text. APRS requires you to locate a star or obtain your phone's location in order to work, which is acceptable. When starting up, searching for stars takes between 30 seconds and 1 minute. Also, the N76 simulator cannot be used to play digital audio.
878, I only see that the second generation of this machine has Bluetooth and APRS, and its power is higher than the N76. If you want to use digital mode, I don't have an 878 device, so I can't evaluate this machine.
Also, the after-sales service from Winno is quite good. When I have a problem, I can provide feedback, and they are able to resolve it. I am one of the first owners of N76, N65, and 6900 machines. The machines needed to be returned for repair, but Mr. Zhang always initiated the process, and the after-sales service was very helpful.