Titles like Beyond the Beyond, Brave Prove, and Thousand Arms remain trapped on the PS1. Alundra 2 & Koudelka are examples of great sequels but were not re-released, missing modern platforms.
Alundra was a short-lived series of action RPGs on the original PlayStation, and was obscure enough that fans were very pleasantly surprised to see it get a shoutout in 2024's Game Of The Year.