OnePlus does have a dev seeding program they just don't publicize it. The Redmi K20 Pro is a great phone and I can't recommend against it. It already has proven it will have a thriving developer community. However, its official support won't last as long as the new Nord, so make of that what you will.
This should have all you're looking for: https://pastebin.com/raw/8fQeL7YM
Google Phone app does support call recording but not in all regions and not enabled on all device models. I live in the U.S. where it's not enabled, but I can't tell you about Europe or India.
Have you tried enabling it, simply by changing regional settings to India? Could you try?
That is the feature for me that i need to have, i recieve orders of customers by phone. And without a call recorder i will not buy any phone.