Is it possible to:
Change geo location on linux vm (which I can do)
Install open VPN on linux and connect iPhone to this VPN.
Change iPhone location to whats setup on linux? Is it possible?
Yes, but it also depends on what data your service relies.
A service relying on your IP might be fooled; but an app on your phone requesting precise GPS data won’t.
I wonder if there are VMs for iphones… seems like the best shot for me if the detection is not IP-based.
It would be so much more easier to pull off on Android, the land of freedom 
Geolocation is done by geolocators, not by VPN.
Maybe you are talking about faking GPS location?
Thanks, it’s an app on an iPhone.
Check if there’s Android version with ability to use the same account. IPhones are digital jails, can’t do much on unmodified ones.
Last i looked (when playing Pokemon Go) there were a lot of spoofer apps directly on GooglePlay and due to me having Android 6 (which had a vulnerability) it worked without root mode, don’t remember if it required developer mode, but it was enabled. Frankly enabling the developer mode is usually pretty easy, haven’t seen a problem with that (maybe Samsung phones? Samsung is Apple in the land of Androids, and i don’t mean in a good sense).
The developer mode gives you an ability to use mock GPS locations, but most serious enough apps i’ve seen are able to detect that, so to spoof properly you’d need a root mode (rooting the phone), maybe you’ve meant that.
Well, for Android there’s a lot of emulators, and i’m sure some of them have to ability to spoof GPS location. Oh, that’s an idea actually, u/OP if that app is multiplatform and you can use the same account — try it using Android emulator instead!