Is Ecowitt owned by Fine Offset? If they ship from hong kong I can certainly save a lot on shipping.
Yes. Although I'm not sure on how their financials are set up to actually demonstrate this to be true or not. Doesn't matter. Another aspect is that the same people work for both Fine Offset and Ecowitt and they are both in Shenzhen. Ecowitt is the only Fine Offset clone seller with access to all models and all parts and any in any radio frequency. In contrast buying from Ambient, Misol, Froggit,...etc. only allows you to buy what they decided to carry and in the one frequency they have for their market.
Also will have to do some research on the ambient section to understand the feature and compatibility differences between ecowitt and Ambient.
It is pretty simple. Any Fine Offset clone console is compatible with any other Fine Offset clone sensor as long as the frequency is a match. With the exception that an Ambient console is only compatible with Ambient branded sensors, as they have modified firmware which purposefully limits compatibility. Available frequencies are 433, 868, and 915 MHz and depending on where you live there are bound to be some restrictions as to what frequency you should use.
Ecowitt console with Ambient sensor works, as long as you are using 915 MHz.
You can't change the frequency of the hardware. The frequency is determined by an actual physical PCB mounted crystal that is part of the actual device.
and also figure out what to do with my WMR200 and WMR88 consoles...
Retire it, put it in a museum, sell it, donate it, or trash (recycle) it.