Great news, dude, you can upgrade all of that covenant gear to 197! So any alt can get full 197 armour and a 187 weapon just by catching up on their covenant. Jewelry, trinket and dual wield toons will have a harder time still, but it is a great step up from previous expansions. (and in Legion I couldn't even play my own spec due to bad Legendary drops, let alone being able to change spec, or even worse level an alt. Early Legion was super RNG based)
The Covenant pets (especially the Slime/Jelly Cat) being covenant bound is especially disappointing because the Nine Lives achievement and its toy (that IIRC only works with the slime/jelly cat pets) is obtainable by anyone regardless of covenant and progress is account wide, but the toy is pretty much unusable if your not a Necrolord, unless theres a second slime/jelly cat pet im not aware of.
if you don't engage with the sanctum, torghast, the maw, or the great vault then this expansion is super alt friendly...
I don't know about the others but Trootie can't battle (it doesn't say it cannot in the tooltip). The slot is blank if you take it to a battle, even with the Night Fae that purchased it.
I bought one yesterday. My pet battle alt can see it but not summon it.