I don’t know what the other guy is referencing, but I’ve been keeping an eye on a company called LiquidPiston, who are developing a modified Wankel, and the seals are one of the problems they talk about tackling. This article from Ars is kinda recent and goes into it a bit: https://arstechnica.com/cars/2023/11/this-inside-out-design-solves-most-of-the-rotary-engines-problems/