Yes I had thought about CE approval. However US manufacturers already are used to getting CE approval and I personally expect the UK to trust CE approved products even after Brexit.
For what it’s worth there is a similar UK standard run by the British Standards Institute (BSI). See - https://www.bsigroup.com/en-GB/kitemark/product-testing/
Regarding Wireless standards, in the UK this is enforced by OFCOM. The intent is to ensure banned frequencies are not used, this is either to prevent conflicts with other registered uses or keep frequencies clear for the military etc. apart from choice of frequencies there are also rules over signal strength, in some cases the US allows stronger signals than Europe.
Due to these issues Eero mesh WiFi products are illegal to use in Europe and sadly they - another US manufacturer have continuously failed to produce legal products even though they are now on generation 2.5 of their products. In the case of Eero I am starting to feel they have left it so long (and still not done it) that they are now in danger of withering away and going bust because other companies like Google, NetGear, Ubiquiti, and so on have all since produced legal mesh WiFi products for use in Europe. A lesson other US manufacturers in other segments should learn from - hint, hint.
What makes this so frustrating is that for wireless standards the chips used are the same ones used by other legal products or at least versions of those chips from the same suppliers. So it is not a matter of inventing something new it is merely a matter of ordering a likely different model of the same chip from the same supplier. It may even in some cases be exactly the same chip but simply configured via software to use different modes/frequencies.