Yeah could just use Google Maps on the GrapheneOS device works with or without Play Services and only uses GPS/GNSS no network location from Google unless you want it.

OSMAnd+, Organic Maps are just two other options.

As far as Calendar goes, Fossify fork of SimpleMobileTools Calendar for on device might work if they keep it updated. However if you're a Proton user that avenue is good, I use Tuta's. Both support importing .ics.