Here is what I have learned about the Dragon Quest XI S compression:
Files have a ZIP value of 03 in Unreal which has previously corresponded to Oodle. Based on their relative complexity they do seem to be Oodle or similar; some form of LZ compression, separate streams for literals/control/lengths in some cases, varying degrees of legibility in the literal stream (e.g. bit literals vs byte literals). I can't rule out that byte 2 is just the Oodle enum but the files aren't parsing with existing scripts. The longest files seem to have a chunk header of "2D03" and the shortest have a chunk header of "2D00" which would correspond to LZHLW and LZBLW, which seems like it's flipped if anything.
Here's an example. The "E2 2B" in the below is the (little-endian) length of the first block beginning with "08 00". It appears to be an offset/length/control block (near offsets?).
2D 03 00 00 00 E2 2B 00 08 00 0F 00 15 00 13 00
1D 00 34 00 0B 00 31 00 17 00 34 00 66 00 96 00
A3 00 29 00 2A 00 C9 00 99 00 AD 00 0B 01 40 01
88 00 CF 00 0E 00 B6 00 80 00 7D 00 E1 00 0E 00
I'm not including a file atm since I don't want someone to break the compression for me, just ideas on what it is if not Oodle or how to get this decompressed with existing avenues. No luck with outside programs so far.
EDIT: Looks like "lizard" may do it, thank you for your quiet support on this journey. Attached is a working script for Dragon Quest XI S
(the Switch version of the game).