Yes, but you do need to do your sums to get them to work.
Have done a few 26” with 29 & 650 rear ( shortened rear shock, offset mounting hardware, and shorter fork, 62 ha at most extreme setup)
Current sonder transmitter will have 29er front but with 42mm offset forks.
& yes mullet isn’t the best name for them setting up with a bigger wheel at the back would be a right pain in the arse ;-)