I wonder if the full disk encryption will take boot time - as encryption is also part of the android boot up. In fact, I am not sure if it even will rob the general performance.
The i.MX8X seems to have aes, for the i.MX8M I didn’t find something
However for launch fde is not scheduled as mandatory at launch (from https://forums.puri.sm/t/full-disk-encryption-performance-in-librem-5)