Can US citizen transit in Schiphol enroute to UK? (two questions)

My US wife obtained spouse visa for UK however flights to Manchester, UK from Detroit seem to transit in Amsterdam. Can my US wife transit Amsterdam enroute to UK? Information on US.gov seems to just say transit through Amsterdam is allowed if final destination is outside the EU, and it's up to the Dutch authorities to decide to allow onward travel to UK.
We found another flight from Detroit to Heathrow with a stop in JFK. If my wife lands in Heathrow, I could drive down and pick her up however it's a 4-5 hour drive from Liverpool. Would this cause issues at the border for her - the fact she is going to self-isolate in a location 250 miles away? We are not making any stops however I do think Border Force would take issue with this.

Finally, if anybody has made the journey recently from the States to the UK could you please give some advice on how you did it and where your layover was, and if you had any issues. We used to regularly fly Detroit to Manchester with a stop in JFK or Philadelphia however no flights with this route seem to be available.

Thanks.