Due to growing interest in potential monopoly situations in the technology sector, not to mention privacy, Apple politicians are in the lead this time.
Log in to your Apple account here to transfer
All you have to do to transfer is visit the "Data & Privacy" service and log in. There you will find "Request to transfer a copy of your data". Furthermore, you log in to the desired Google account, give some rights to, and that's it.
At the same time as you are presented with how many GB we are talking about, the number of images and the number of video files are listed.
Note that it can take up to a week to get the data
Nothing is deleted from Google Photos, but please note that RAW, Live Photos (still image version only), and Smart Albums are not transferred.
You can also download data from a number of Apple apps, deactivate your account for a while, and delete it.
Sources: 9to5Google