okay i know it isnt possible for them to be actually related.
i was re-watching the lion guard clip and when bunga said "you know what my uncles always saying!?" then kion says "Hakuna Matata" could this possibly mean he is? or meaning bunga is a good friend of pumbaa.
im also basing this off the 'Bunga the wise' cover we saw a few weeks ago with timon and pumbaa beside bunga