To add to my post, I'll also say that given the fact that these are >$70k vehicles, I find it hard to believe that an oil service is going to bankrupt anyone.
Dealer service department hourly rate variability between geographic location is literally like playing roulette. There are Euro luxury brands that charge $120/hr in one part of the country and $230/hr in others. Combine that with a routine "medium" service (disclaimer: this is for a generic vehicle, NOT the Grenadier, since that isn't officially published to my knowledge) which will run ~5 hours of shop labor (oil service, engine/cabin filters, tire rotation, brake fluid flush, overall vehicle inspection, wiper blades, etc) and you have a difference of $550, solely because of where you are in the country (or what actual dealer within certain regions as well).
For strictly an oil service, I would expect something along the lines of: $115 in parts ($24 filter, $13/qt for oil using OEM list BMW pricing), $10-15 in shop supplies, and 1hr of shop labor. Could it be less than 1hr of labor? Absolutely, but some non-Ineos dealers have a minimum labor rate of 1hr. If this is crazy, consider spending a few moments and finding a highly regarded independent shop that specializes either in these vehicles or knows what they are doing to work on your vehicle instead.
Again, THESE ARE NOT INEOS PRICES! This is an example based on my experience of working in the European automotive performance/service world for nearly 20 years