@doctorbadwolf The thing is, for me, what I like about the little folk is really hard to quantify as active abilities, and in the D&D framework are usually hard to quantify at all. For me, it's their resilience to corruption, (usually) community-focused lifestyles, and love of food. In certain other systems those are all able to be represented with clear mechanics.
Mechanically, I love their luck, but currently that's more reactive (turning failure into potential success) than active. Giving them the Lucky feat would make it more active. Stealth as an ancestral ability is something that's already given to a lot of the 'small' races, and is also hard to make an actual active ability. Unless we really lean into our original burglar and give them the ability to straight up turn invisible (proficiency times per day seems to be the new default).
Heck, we could REALLY lean into their association with invisibility and make them able to see invisible creatures, too (as an active or passive ability, either or).