Looks like the BL602 is already used in controllers for RGB LED strips.
Unfortunately the listings on AliExpress don’t tell whether they have an esp8266 or an ble602 inside.
Would be quite nice to get more information about it. I commented on the Github issue. Would like to get my hands on one of these. In long term it would be quite nice to get RIOT running on it. There are also some people struggling with connecting it to their smart home systems. So, maybe this is also a good strategy to get more people into RIOT.