I haven't figured out how to find good photographers to follow but my last two posts there has both gotten over 25 likes which is more than I used to get on Instagram so I guess that's something. My only complaint is how much they scale down my pictures and absolutely butcher the quality.
Also consider that Instagram uses aggressive image compression and then you import from that to Pixelfed, which also does its own compression. No wonder the quality is questionable.
Have you tried adding an original image to Pixelfed?