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I've enambled google location accuracy in sandboxed Google Play settings and yet have to test if this works a lot better than before (the setting claims that if turned off only the GPS is working, although I don'n think the location accuracy was THAT bad).
Unless you want to use the Google network location service to provide location without satellite reception, such as indoors, you shouldn't enable this. Enabling this without granting the Location person and disabling location rerouting doesn't do anything.
Google Play Services - Network, Phone, SMS, Sensors
Why give it access to Phone and SMS? You can disable Sensors unless you use apps requiring their Sensors API too, which you likely don't need.
Since you haven't granted Location, which is fine, you depend on the location rerouting feature for location detection and should therefore disable the Google Play location accuracy feature which will not work without granting background Location access and Nearby Devices.
Location services - wi-fi and bluetooth scanning off
This doesn't make any difference unless you have an app granted background location access which uses Wi-Fi and Bluetooth scans for network-based location. You haven't set this up for Play services, so it doesn't make a different whether it's on or off. They're off by default particularly since there's nothing to use them by default.
Secure User Plane Location (SUPL) - enabled GOS proxy (stock)
Predicted Satellite Data Services (PSDS) - enabled GOS server (stock)
There's no reason to change either of these.
So do I have to change anything with the above, mainly SUPL and PSDS? Also, does it make any sense to give location permission to Google Play Services?
You don't need to grant the Location permission to Play services unless you want to use their network location service and disable location request rerouting for the sandboxed Google Play compatibility layer. You do not need to do this unless you want to use their network location for even quicker location fix outdoors and indoor location detection, so don't do any of this unless you want that. The documentation explains how to use the network location service: grant background Location and Nearby Devices to Play services, make sure it has a battery optimization exception (which is also needs for FCM and other things anyway), disable location rerouting so that app requests actually go to it from apps using the Play location API, enable their network location accuracy toggle and enable Wi-Fi / Bluetooth scanning so it can scan for them in the background when they're otherwise disabled, not just GNSS (satellite) location and cell towers.