I'm happy to agree with the two previous speakers, the P30 Lite takes great photos for a lower mid-range phone and it runs smoothly. There are great cases at apfelkiste punkt CH. They protect the phone better and give it a good grip.

I don't know the Mate 20 either. In any case, the camera takes very nice pictures and the P30 Lite runs wonderfully smooth... In general, a device of this new size class should not be used without a case, as the risk of falling is latent. With a case and glass protection, nothing ever happens - even if it does fall.

Since I don't know the Mate 20, I can't judge whether my P30 Lite is better. However, I can recommend it, but I am not a photo professional. The only problem is the very slippery glass back. I've already dropped the thing twice, and the back has two cracks at the corners as a result. The display, however, is undamaged. A cover is therefore recommended.
The one that came with the phone soon became unsightly.