This decision was promptly copied by every other major phone manufacturer, for the same reasons Apple made the decision. The 3.5mm jack is obsolete and getting rid of it enables a better, tougher device which is more waterproof.
The idea that this was about waterproofing is a fabrication.
No phone is more waterproof with it than without (they all have complex data ports with many connection vs three or four in a jack). No phone has a bigger battery. No phone is tougher.
It allows Apple and others to sell expensice Bluetooth ear buds.
And yes, I do own a pair of airpods.
https://www.teamandroid.com/2019/05/16/google-pixel-3a-water...
Far easier than for a USB port, I'd say.