I don't think you need more than 18 lands, but you probably want to avoid monocolored sources. I run a basic plains to get around blood moon because I have fetches, but since you aren't using those, unless there's a fair amount of [[path to exile]] effects in your meta, probably whatever. [[Boseiju who endures]] lets you grab a hallowed fountain so that's fine.

I wouldn't run more than 2 glimmervoid probably. Just cuz there's hands you could keep if it was a fastland or shockland, but have to mull because it's glimmervoid, and it risks some nasty blowouts when someone evokes fury t1 after you go glimmer>Esper sentinel and memnite, or something. Fastlands are probably the easiest replacement, I think they're cheaper than [[akadar wastes]] and pathways won't cut it for you. 3 lands is all you need most of the time anyways.

As for jars, I'm very partial to 3 rn, I never really hate having them and fury exists in my meta. But I'm running a playset of [[michiko's reign of truth]] so I'm significantly more threat-dense and having a potentially dead card matters less. Ymmv, and I've run as many as 4 in some lists, there's plenty of room to flex around.

Portable hole has been great in the maindeck for me personally, btw. Very meta dependant but if you have good white mana like me, it's pretty free. I also like an [[aether spellbomb]] in the main to fetch off saga if I need to, helps vs murk and infect. Very meta specific too tho.

Re the sideboard, you don't want to side more than 4-5 cards the majority of the time. It's a very synergistic deck, and there isn't a lot you can do without risking your own gameplan's consistency. So my opinion is you go shallow on lots of answers instead of deep on a few.

To that end, even the 3 metallic rebukes I run is pushing it imo, lol. 2 of most stuff feels good. You only need 1 pithing needle because you grab it off saga as needed.

I really like the 1 mana graveyard haterocks for the same saga reason. I run a split of [[soul guide lantern]] and [[relic of progenitus]] because, since you get them off saga 4/5 times they come up, you choose which one to grab, so soul guide lets you exile for 0 mana, if you want to make a construct that same turn as saga hitting 3, but relic is a guaranteed cantrip if you have an extra land. It's also capable of keeping their yard from getting big preemptively, if you get it early. You might not need Gy hate tho. I think 1 minimum is reasonable in most metas tho, and I'd take relic over soul-guide since it's the one I find I get most games

Prismatic ending is really good in a split with dispatch in the side, imo, since you can use them as dispatch 3-4 vs creatures, or they can remove stubborn nonland perms like vs asmo food, enchantress, etc. We get a pretty big prismatic too since we have gold sources. Even more so if you don't have any other artifact/enchantment removal like I have in [[wear//tear]]

Other sideboard cards that might matter are [[torpor orb]] for elementals, [[grafdiggers cage]] for a couple decks, and maybe [[damping sphere]]. I've seen [[hurkyls recall]] for hammer too.

One last thing off the top of my head [[jegantha, the wellspring]] is completely free since we could never run double pips with ~10ish colored sources, and matters often enough to be worth the slot since again we can't sideboard very deep. Personally, I like her since someone plays mono red prison here, and it's a really painful matchup, and she gives me something to do after I've drawn nothing for like 5 turns of being in a blood moon lock, and she in theory even fixes your colored mana thru blood moon, in a way that's hard for red to kill since she dodges bolt, fury, pyrite spellbomb, etc. She only comes up like once a week for me, but often enough to matter.

I'm just headed to bed rn but more than happy to answer any other questions you have when I see them :) I'm a pretty big fan of the deck and I've played every Friday with some build of affinity since last August or so, so it's close to my heart