For 40k, OP 11R does look like a decent choice. Sadly not many good phone options beyond 30k, any S888 or SD 8 Gen 1 SoC phones are an easy no because of lower efficiency. SD 8+ Gen 1 has better efficiency than those. Camera should be fine, don't expect the best camera for this price & you will be fine.
I will any day prefer Samsung's one UI over oppo's UI, but no good Samsung phones around this price. If Samsung had a S22 FE with the same specs as S21 FE but Dimensity 8000 under 40k, would have been a great choice easily.
Sadly Apple killed 3.5mm jack and after few years, everyone else followed. BT neckband or TWS are the way to go now for audio.