DnDBeyond is probably the best solution
DnDBeyond is WotC's official digital location for rules and material for 5e. However, you must purchase any material that is not part of the Basic Rules/SRD in order to see details from that source. However, it has search functionality that seems to meet your exact needs.
By going to the magic item section and selecting "advanced search" you can do searches by many different parameters. Here is an example search for items that do fire damage.
The search results will show you a list of all items that meet your search criteria regardless of what you have purchased digitally. But you will only be able to see the details of that item if own that digital source. You can actually buy just that item from the source if that is all you are interested in as well.
You can't use modify memory, but if you found another way...
From MikeQ's answer, a revenant is immune to the charmed condition, which makes it immune to the spell modify memory. But if you were to find some other way to alter a revenant's memory, one which bypasses its immunity to the charmed condition (wish is the obvious answer, but there are better wishes the BBEG can make so you should probably devise a more original solution. Maybe some ability which lets the BBEG ignore the charmed immunity on undead, if he's a necromancer), then there still remains the question of whether an altered memory will change the revenant's sworn targets.
The description of the revenant in the Monster Manual (p.259) says that
No magic can hide a creature pursued by a revenant.
However, it says nothing about magic's ability to make the revenant pursue a different creature. On one hand, one could argue that a revenant is fueled by a soul's desire for revenge, regardless of whether it is correct or not, and that it only matters who the revenant believes has wronged it, regardless of whether the target is actually guilty. This could apply if revenants emerged from some process independent of external agents. This view is supported by the first paragraph of the revenant's description, which describes the soul acting by its own agency. If this is the case, then altering memories could alter a revenant's target.
On the other hand, it is possible that a revenant's target is fixed from the moment it is raised into undeath. The following two paragraphs of the revenant's description, Hunger for Revenge and Divine Justice, hint at this powerful supernatural link between the revenant and its target. If revenants are raised by a god so it can enact divine justice, then no mortal effort could alter the target. If this is the case, then altering memories will not alter a revenant's target, but it might leave the revenant rather confused.
So either case can be argued to be correct. Whichever way you rule, you should be consistent. If the PCs learn that revenants can have their target changed via whatever means the BBEG used, they might use this tactic later if it uses abilities and items which PCs acquire, although since NPCs are not PCs the BBEG could very likely be using some ability which is beyond what is available to PCs.
But since there is no rules-as-written answer to the revenant's behaviour (at least, not that I can glean from the Monster Manual), the real question becomes 'which option makes for a better story?' In my opinion, having the BBEG trick a revenant into hunting the party by using memory modification is a cool story and you should do it. Note also that there are multiple possible outcomes to this plot. Beyond combat, the player characters might be able to detect and reverse the curse which was placed upon the revenant, at which point they would gain a useful ally and strong lead towards the BBEG. This sounds like a brilliant plot arc and you should do it. Even if the official revenant description opposed this plan, you could overrule it to make for a better story.
Best Answer
Use Detect Thoughts guided by an interrogation, followed by Modify Memory
You've stated that that neither Detect Thoughts nor Modify Memory does what you need, but what if you used both of them together? First kidnap the target in their sleep. Then wake them up and have one person cast Detect Thoughts and focus on reading the target's thoughts while another person interrogates the target. Whether or not the target lies in their answers, the Detect Thoughts spell will likely get the information you want. Waking the target up and interrogating them is necessary because even if you probe deeper, Detect Thoughts can only tell you what the target is thinking right now, so if they aren't thinking about what you're interested in (or dreaming about it, if they're asleep), you're out of luck unless you have a way to guide their thoughts toward the desired topic.
Make sure this whole process takes no longer than 10 minutes (the maximum length of a memory that can be modified). Then, cast Modify Memory and erase the target's memory of the whole process, instead making them remember being asleep the whole time. Then, use some means of putting them back to sleep before the Modify Memory spell ends. Since the spell makes them "incapacitated and unaware of their surroundings" for the duration, they will have no memory of being knocked out, in addition to having no memory of the interrogation. Finally, sneak the sleeping person back into their bed. When they wake up in the morning, as far as they know, they have slept all night uninterrupted.
Note: don't use Modify Memory to make them think it was all a dream, unless you want all the townspeople to compare notes and eventually realize that they're all having the same weird dream about being interrogated. Just erase the memory entirely.