On my device the location service is not working at all. Neither in the Weather app, nor in apps like puremaps or uNav. Does anyone else experience this issue?

Halium recovery does not clear the cache completly. For a new device it is necessary to install TWRP first after unlocking the device. It can be downloaded from here: https://dl.twrp.me/suzu/twrp-3.3.1-0-suzu.img.html and flashed in Fastboot Mode (Power on + VolumeUp = Blue LED) using:

fastboot flash recovery Downloads/twrp-3.3.1-0-suzu.img

Afterwards boot into TWRP and select Wipe / data, system & cache partitionen. Continue with the installation (OEM Binaries / UBports installer)