So before this shuts down, is there anything good that is exclusive to the PS3 Store and worth grabbing before it is gone forever?

50+ Digital PS3, PS Vita Games to Buy Before It's Too Late | Push Square

Not sure about good but here is a list of recommended games that are either store exclusive or cheaper to get on the stores. To sum a part of the article up

PS3 + Digital Only

Blast Factor

Bomberman Ultra

Calling All Cars!

Linger in Shadows

PixelJunk 4am

Those are what I know of.

I would just say every single PS1 and PS2 game. A lot of those games are expensive to get if you want the physical copy, but on PSN they're $5-$15. I just grabbed Fatal Frame 1-3. Also here's a few expensive ones. Silent Hill, Vagrant Story, Arc the Lad 1-3, Armored Core, God Hand, Chrono Trigger, Dino Crisis, Ape Escape 1-3, Xenogears, etc.

I'd also look into other digital only games that you cannot get on current platforms, or if you only game on Playstation then not on PS4/PS5. Off the top of my head there's the Dreamcast games, Ratchet and Clank Quest for Booty (EU has physical), Dead Nation, Adventures of Mana, Sonic the Fighters, Sonic 4, etc.

If you wanna get "classic" games you didn't think that were on PS3/Vita, but are just digital only even though they're available on PS4/PS5. Shovel Knight (cross buy), Shantae Half Genie Hero (PSVita), Attack on Titan, Yakuza 5 (PS3), Resident Evil 0/1/4/CVX (PS3), Steamworld Dig 1/2 (PSVita), etc.

What hurts the most is the PS1 and PS2 games since the PS4/PS5 has no where near the selection of retro games.

I would like to add Ratchet: Deadlocked to your list. The PS3 version doesn't have a physical release, so if you want the PS3 version in particular, now would be a very good time to start thinking about it. I don't think the PS3 version is considered as good as the trilogy remaster, but I had a good enough time with it anyway.

I'd also like to add that some old games, like Chrono Trigger and Dino Crisis (also DC2), are available on PC as well and probably don't require powerful hardware at all. Such games won't be entirely lost then, although for some of us, PC might be more or less of an inconvenience.

PS1 and PS2 games bought from PS3/Vita store in particular are one of the reasons I look down upon Sony so badly these days. There's no good reason to not allow playing those games on PS4 and PS5 as well, it's just poor treatment of us customers.

I'm not going to make a new post for every discovery or observation I make but this one is a pretty big one.
Infamous: Festival of Blood is a digital-only standalone expansion of Infamous. It's cheap (4.99) and it's better to get it on the PlayStation Store and play it natively on PS3 than use PS Plus Premium.
Both core games and Festival of Blood are bundled together for 14.99 if you don't want physical copies of the two core games. That's still pretty cheap and I might get it soon instead of hoping for a last minute sale in the closing days to month of the store.
Xbox 360 and 3DS/Wii U had some great sales when they closed but with how broken the PS3 and Vita storefronts are I would not bank on that.

The PS3 and Vita store hasn't had a single sale since 2020. That's because Sony stopped allowing discounts on those stores for whatever reason. If you want something you have to buy it at whatever price it is. The only games that you can get discounts on are the cross-buy games if there's a PS4 version with it. You'd have to buy the PS4 version to get the discount then go to your Vita/PS3 to download the game.

So yeah everyone, do not expect discounts before they close.