SG Playstation store not so terok like the Nintendo one, has like 99% of the content in the USA store.
Just did a check on my US PSN account, there are roughly 250 purchases on record. Around 1/5th of that are for the old PS3, PS Vita & PSP.
Out of 200 odd US PSN titles for PS5/PS4, around 60 of them apparently not found in SG store.
Below is a brief breakdown:
- There are 7 Cotton games (classic arcade shootemup) in US store but only 2 in SG.
- A few of the games I have are like just announced or just launched recently in SG store, e.g. Andro Dunos II, Ganryu 2 Hakuma Kojiro, Car Mechanic Simulator, Dungeons of The Deep. Note that they only costs me US$1.79 to US$2.99 each as I bought them during heavy discounts back then.
- Below are games I've purchased that are older versions from their respective game series, seems like many older versions of game series were not released on SG store compared to US, i.e. Sniper Elite V2 Remastered, Sniper Elite 3, Sniper Elite 4, Shadow Warrior 1 & 2, The Walking Dead Season 1 & 2.
- SG store also randomly skipped inbetween game versions, e.g. they have Wild Arms, Wild Arms 2, Wild Arms 4, but no Wild Arms 3 (which I've bought).
- Many US games in my library are arcade/shootemup/beatemup etc which weren't present in SG store, i.e. Night Slasher Remake, 9 Monkeys of Shaolin, Cotton Fantasy, Cotton Reboot, Rainbow Cotton, The Hong Kong Massacre, Cobra Kai Rhe Karate Kids Saga Continues, Project Root, New Star GP, Retro Machina, Sword of The Vagrant, Ara Fell Enhanced Edition, The Takeover, Fury Unleashed, Zombies Ate My neighbors & Ghoul Patrol, Sturmfront The Mutant War, ADK Damashii, Metal Slug Anthology, plus a whole bunch more!
- Some classic RPG/dungeon crawler games purchased in my US library, Crystal Rift, Vaporum & Vaporum Lockdown, The Bard's Tale IV Directors Cut, Earthlock, Operencia The Stolen Sun, Knights of Pen & Paper 2, Vambrance Cold Soul, Demon Gaze II, Bastion etc.
- There are games on SG in Chinese only where I bought the English US version, e.g. Valkyrie Chronicles.
- Some interesting and unique titles, Firewatch, Submerged Hidden Depths, Yoga Master ( I actually went for quite a few yoga lessons many years back), The Wolf Among Us etc.
- I would think Olympic Games Tokyo 2020 by SEGA is a pretty big title, not sure why it wasn't in SG store.
Above are just based on my own experience, on titles I've bought in US store, others may of course have a different summary depending on their game preference.
My recommendation is to have both SG and US accounts on your PS5, wishlist all games you are interesed in on both PSNs, and check them when there are sales. Sometimes when games are on sale on both stores, the US one can be much cheaper. The same can happen the other way around though less often.