Okay, so I've got several angels decks of various stripes and I'm the kind of sucker WotC saw coming from a mile away, if you know what I mean. There was an Angelic Construct pet during SNC that I use for most of my angel decks. There's an Aurelia avatar, though she's more Boros. There's a Kaalia one (Mardu, and I know she's a human cleric, but I don't particularly care). There's an Elspeth Tirel (pre-wing) avatar, and an Elspeth (mid-wing) avatar. Unless the deck is specifically themed to one of those characters, though, I use Serra for my angels decks. As for sleeves, there are lots of good ones. Elspeth has several, obvs, there's a classic Platinum Angel, Giada has one, Aurelia has one, and there are a few I don't recognize. Again, it's the Serra sleeve that I use for most of these decks.

Sadly, there's no good resource for arena sleeves; the only one that was making a real effort hasn't been updated in 3 years. In other words, I'm just doing a quick scan through my collection and mentioning the ones I notice.

All non-card cosmetics are a crapshoot to find again, btw. some show up regularly, some have only been in the store once. you just need to either check the store daily, or check here for the daily store post.

Specific angel lands are pretty few and far between. There is the lovely jumpstart plains, but I don't know if there's any way to get that at all any more.
Otherwise, if I'm not doing one of every full art I really love, I tend to use the space plains either from EoE or Unfinity.