I was able to speed up RAIDZ Expansion on 24.10.1 up to 220MB/s with this command
echo $((30 * 167772160)) | sudo tee /sys/module/zfs/parameters/raidz_expand_max_copy_bytes
1677721600
from this thread RAIDZ expansion speedup
RAIDZ1, 3×4TB → 4×4TB in 12 hours
(I was very surprised when I first see a 2 weeks ETA on this expansion haha)