HUAWEI phones, starting with the Mate 30 line-up, are shipping without Google Play Services, and all the early workarounds to get GMS on devices have eventually stopped working.
It seems that there’s a new way to get Google Play Services on HUAWEI smartphones. However, the usual warning goes without saying that this is not an official method, it could impact your privacy, and it might not work on all HUAWEI devices.
You’ll need to download a certain Chat Partner app (an APK of roughly 150MB) and launch it. It will give you the option to Detect Device, which you should hit, after which select Repair Now, followed by Activate on the Device Administrator window pop-up.
Installation will begin, and, after a reboot, you should have access to Google Play Service. When you see the Play Store, you can uninstall the Chat Partner app.
If you’re getting a “Device is not Play Protect certified” error, there’s a workaround detailed here.
Of course, always remember the warnings at the beginning.