Mediatek GSM/HSPA/LTE capable CPU.
Cheapest phone I have found so far is ZTEObsidian. There is another developer working on the postmarketos with another MT6735 based device.
- Plug in Micro USB cable
- remove battery
- start a bootloader tool like simple-serial.py (very much work in progress tool to report chip-id on various mediatek devices)
- press up volume button until beacon response is given and chip id should then be reported
config block seems to be at 0x20000000
chip id at 0x20000008 reports properly as 6735