“Sideloading” isn’t a thing. That’s a term to shame and discredit people and apps installed outside of the official stores. Just like people got shamed by “jaywalking” for merely crossing the street. Both of those things were, are, and always should be the norm.
Because it isn’t real. You aren’t “sideloading”. You’re simply installing apps. You’re not doing anything different, other than using a source that the big company does not like.
It needs a definition because it is a thing that happens though.
You need to differentiate between installing from the app store and installing from other sources, you might not like the choice of word, but we need a word to define it.