The more I read, the more I run into most if not all Xiaomi and other phones that you listed don't support Widevine L1 (a copy protection system for video.)
Since this is a rather common thing to do on these phones, be sure to get Widevine support.
which Gaming Phone is better? Xiaomi Black Shark Vs Doogee S70
Similarity: Released in 2018, gaming phone, GPS, Android Oreo. 5.99" display, fingerprint sensor, 4G LTE
Xiaomi Black Shark is better: Powerful processor, more RAM, Slimmer, great cameras, less weight, good GPU
Doogee S70 is better: big total memory, NFC, bigger 5500mAH battery, IP68 / IP69K / MIL-STD-810G, Gorilla Glass 4, the price is less than $300
Xiaomi Black Shark price is double to Doogee S70, but It has a powerful processor GPU and great cameras. On the other hand, Doogee S70 has more battery power, unbreakable ability, game mode button, and NFC Chip.
what about Asus ROG and Razer Phone ?