I wish I could be enthusiastic about Nordic, but it's impossible with their extremely non-free SDK license: https://developer.nordicsemi.com/nRF5_SDK/nRF5_SDK_v12.x.x/d...
The first three clauses are fine, essentially BSD-3-clause. Clauses 4 and 5 make it extremely unfriendly to free(-as-in-freedom) projects though. I don't even understand how clause 5 benefits them.
Espressif's devices are definitely not open in any sense of the word, but at least their SDK is under a bog-standard Apache license. Same goes for most of the STM SDK.