£60 for better graphics and a little bit of story?
The "game in installments" thing is going how I thought it would then
It's not £60.
Intergrade is for people who don't own remake that is an all in one version of remake on the PS5 that includes the Yuffie Episode.
Final Fantasy Remake on the PS4 will be upgraded for free to the PS5 version. eg: if you bought the digital version of remake on the PS4 you won't be able to purchase Intergrade due to the free upgrade eligibility on the PS store. If you bought the disc version it's also a free upgrade, but obv if you try to purchase a digital copy of Intergrade your account history won't show you own remake and let you purchase a second copy.
The Yuffie episode is the extra DLC. This can be purchased separately either after you upgrade remake to the PS5 version. The price for this hasn't been given to us so it's all speculative atm.
People are outright jumping to conclusions.
edited: Yuffie Episode is PS5 only as it hasn't been optimized for PS4. IGN incorrectly reported it was PS4 before Square clarified it wasn't.