1. How long does size, encode time and resize take compared to good old jpeg?

2. Is it possible to encode AVIF with hardware acceleration?

JPEG is fast as fuck, due to it being designed for decades old hardware.

When it comes to hardware encoders, the nicest thing you can say about them is they're fast. Software tends to do way better at quality. Hardware AV1 encoders will be tuned for video rather than stills.