How can victims of a Devourer / Spawn of Kyuss be restored?


In 5e, there are some monsters which can kill and transform / disintegrate PCs. While disassembling the published monsters, I made the following interesting observation:

Some of these state that only a wish spell can reverse the transformation. Examples include the Blue Slaad and the Nabassu. On the other hand, the Devourer’s Imprison Soul contains this extract:

Additionally, at the start of its next turn, the devourer regurgitates the slain creature as a bonus action, and the creature becomes an undead. If the victim had 2 or fewer Hit Dice, it becomes a zombie. if it had 3 to 5 Hit Dice, it becomes a ghoul. Otherwise, it becomes a wight. A devourer can imprison only one creature at a time.

There is no mention of if or how this can be reverted. The same goes for the Spawn of Kyuss’s Burrowing Worm which transforms a victim into another Spawn of Kyuss.

In any case, the part about the wish spells is suspiciously missing for these which made me wonder:

Can the victims of these monsters be restored by methods other than a wish spell? Or not even with a wish spell?