TP1900BN and MT7626B(N) are different names for the same SOC, a single core (but two threads) ARM Cortex-A7 running at 1.2 GHz. It's still very new and as a whole not supported yet. What all known devices seem to have in common though, is the reliance on SOC internal flash/ RAM, which would limit it at 4 MB flash and 64 MB RAM - with those specs I see little (read, "no") chance of this getting supported.
https://openwrt.org/supported_devices/432_warning is a real problem - I don't see anyone wanting to put effort into supporting a new SOC, if all of its devices are below minimum system requirements and limited to that.