when leveling my players, i get alot of questions concerning various BOA items i have. explaining it is overly complex. gating to force past content is defeating, i believe the gating needs to be dropped for Shadowlands, making these available from BOA vendors in UC and IF
WOD
i tell them to look at WOD garrison guides. alot of players do not know what WOD means or even how to get there, the trinket from WOD can be purchased from players in trade chat, but the three rings, require development of a garrison, and then a full scale up of a ship yard. both require quest lines, reputations, farming rares, garrison resources, and oil. alot with time required to get BOA ring missions.
Legion
there is a BOA necklace gated that would have to be acquired thru class hall mission board and developed followers before you would get the mission to pop. there are BOA necklaces acquired for gold in UC or IF from a vendor.
BFA
eight BOA trinkets (4ea faction) and two BOA FP unlock maps for alts. these are all gated of course to the current expansion