I'm surprised no one's mentioned Baraag/Pawoo yet. They're Mastodon instances that allow loli/shota, and Pawoo is managed by the same people who made Pixiv. I get most of my lolisho content from Baraag as you can see that in most of my posts I just link directly to their images.
I don't really have a list of loli artists to check out, so I'd recommend just going through the loli hashtag or to have a look at the list of people I'm following to see if you find anything you like.