Pretty much this. Even with cosmetics most can be directly purchased via in-game currency you earn from getting duplicate cosmetic drops from the crates, Textiles. And you get a crate every 4 watch levels. So you can still directly get a huge number of the cosmetics, with only a handful realistically being locked in lockboxes or for premium currency only in the cash shop.
I actually bought the annual pass for this season (got it free last season because I had a special edition of the game I got for free with my replacement graphics card) and it's darned cheap, $10, and as you said is totally optional with most of the "big" rewards like crafting plans being a part of the free track.
Base game - Frequently on sale for $5 or less.
Expansion - $30 I think, but also frequently on sole for less, and bundled with the base game for a discount as well. It's a solid amount of content included with it for free, and gives access to more free content like the Summit that's coming with the next update.
Season pass - I guess they still sell it, I think all it grants is immediate access to the 3 latest specializations (minigunner, tactician, flamethrower). You can unlock all three in-game without too much difficulty (I've done tactician, on the last stage for gunner, and just starting flamethrower as I largely progress via "accident" in normal gameplay).
Loot boxes - Lockboxes, as they don't actually contain any "loot". Purely cosmetic, and the default ones are granted every 4 watch levels which doesn't take too long to get (especially with double XP for 20 levels after a manhunt update). They occasionally run premium events, but those also seem to come with free keys until you unlock everything. There are separate premium boxes like the one live now that are premium currency only, but meh. Cosmetics.
Item shop - Yep, they allow you to directly purchase stuff rather than just rly on RNG lockboxes. That's actually great! You can do it with premium currency, or with the Textiles you get from duplicate cosmetic drops. Given the frequency you get boxes with normal play you can unlock the stuff you want at a steady clip.
Battle pass - Largely a bunch of cosmetic bonus rewards, with some occasional faction keys for in-game lockboxes, and you can get the keys from doing bounties easily so it's not like they're of much value.
For the number of ways they have to monetize the game, the monetization is surprisingly low-key and not really in your face. Outside of buying the second battle pass for $10, I haven't spent a penny on the game because I honestly feel that I can pretty easily unlock whatever cosmetics I want through normal gameplay. So I get being "sticker shocked" by looking at it all from a distance, but in-action it's probably one of the more fair models I've seen in a while now that they're not charging for each DLC update. Unless they start making DLC expansions for $30 a year every year, I'm totes fine with this approach, even with the slower/smaller cadence of content updates compared to some other games.