Where about are you moving in Switzerland? I've been living in Zurich for several years now, and have bought and owned a few BMWs here. Currently have an M135i and an X6 M50d, with an X5 45e on order (more for novelty factor than much else). If the X7 had come in 45e variant, I probably would have gone that route.
Advertised prices are high (around CHF150k for a loaded X7 40i here), but there are good discounts to be had. Many of the big corporates (with many expat workers) here have fleet discount details with major German brands, so getting 25-30% off can be done. Leasing is also much more common than buying outright here.
In Canton Zurich, an X7 40i will be around CHF900 in vehicle taxes per year. The formula differs from canton to canton, in Zurich it is based on engine capacity and car weight - here is a calculator (in German - note weight is the gross weight ie. max weight capacity):
https://stva.zh.ch/internet/sicherhe...VArechner.html
3rd party vehicle insurance is compulsory, and then there are various add-ons to get up to fully comprehensive (including insurance for damage caused by martens chewing up your vehicle engine bay -
https://www.thelocal.ch/20180504/car...hewing-martens). You are probably going to pay around CHF2,500 per year for fully comprehensive vehicle insurance. It is extremely likely that, to get insurance here, you will need to have your vehicle locally registered and on local plates. I do not know if there might be a premium on a foreign-specced vehicle. Not winter tyres are not legally compulsory; however, if the insurance company believes your claim incident was caused by not having winter tyres, then they can reject your claim. So almost everyone here runs with proper winter tyres during the season.
'Gas' is commonly available in 95 and 98 octane variants. Price has come down a lot in recent weeks due to the 'virus and the Saudi-Russia handbags. But typically, you will look to pay around CHF1.75 per litre, so a full tank (80l) is around CHF140. Keep in mind Switzerland and Europe are relatively small, and distances between items of interest are not large compared to the US. So you may pay more for fuel, but likely to travel less distance on a day-to-day basis.
To this foreigner, there is much less 'peer pressure' on car ownership in Switzerland than I expected. I imagined that car owners would be frowned upon, and if you had to have a car, it must be a 3-cyl diesel hatchback. But in fact, quite the opposite, perhaps given the high average wealth in the country. Quite a few Teslas and eTrons here, but also many straight-sixes and V8s. SUVs in general (including X3s and X5s) are very common, and there are a few X7s around. Roads are likely going to be quite a bit smaller than you are used to, and they are shared with trams, buses, bicycles. So may take a little time to get used to (and you may avoid certain tighter parking garages), but definitely not a deal breaker. However, do consider where you might live (apartment, stand-alone house, in the city or in the suburbs), and factor in the need for (suitably sized) parking.
I don't know much about regulations around import and operation of foreign-spec vehicles, and any adaptation legally required for Swiss roads. These folks might be of service:
https://www.autociel.ch/service/import-a-car/
Might also be useful, as previously suggested, to reach out to a local BMW dealer this side and see if they are able to service a US-spec vehicle. If you're moving to Zurich, I can put you in touch with my dealer if you'd like.