If you manage to somehow force a Zombified Piglin to kill a villager, it will actually infect him even though they normally do not attack them.

Use this:
/summon villager ~ ~ ~

{UUID:[I;0,0,0,1]}

/summon zombified_piglin ~ ~ ~

{UUID:[I;0,0,0,2]}

/execute at @e[nbt=

{UUID:[I;0,0,0,2]}

] run summon snowball ~ ~3 ~

{Motion:[0.0,-0.5],Owner:[I;0,0,0,1]}

This seems to likely happen due to zombified piglins sharing same NBT data as zombies.