Even though the car is a 2020, the only maintenance you will have for a long time is an oil & filter change. If money isn't an issue, use the dealer especially while still under warranty. If you have issues with the car in the future it's best have a good relationship with the dealer service department.
Usually a good place to eat is busy, lots of cars out front. A dealer isn't that much different. If it has many empty bays, and help wanted sign out front, perhaps look elsewhere, for any business.
The dealer will use same oil every time, most likely Mazda branded but is made by someone else. See if you can find out who makes it and continue to use it later when going somewhere else if possible. In other words, don't switch oil brands or switch places you have car serviced if you plan on keeping car for more then a few years.
I have used Mobil "1" since 1985. I have only let someone else do an oil change service once in my 60 years of driving. That one time the guy left the battery caps off and the acid fumes damaged the chrome right valve cover (V8 engine) and blistered the firewall paint. So at 80 I still service my cars so it can't be that hard.