Bedrockgames
I post in the voice of Christopher Walken
With no real pop cultural focus and identity, they're just a big ball of nothing.
Things don't have to exist in mainstream pop culture to be relevant in an RPG though. I think as long as there is a resonant concept or the race serves as a springboard for workable character concepts. Someone mentioned the Jackson LotR, and for me that movie is not a gaming touchstone (it came around much later in my gaming experience, so I tend to be more shaped by movies and books from the mid-90s to the 70s and 60s). Also I don't find Legolas or Gimli as depicted in that film as especially nuanced or interesting (they very much lean into the humor that people complain about with gnomes). And if humor is an issue, the way I see most gamers play dwarves is basically as a joke (beards! Beer! Grrrrr!). Dwarves are basically grumpy grandpas in most campaigns or cartoonishly masculine. Gnomes are more on the eccentric grandpa side of things (and more academic too: I could see a host of gnome characters inspired by famous scholars or writers from the past for instance). Something being humorous isn't automatically bad though. Part of the reason people like dwarves is they enjoy Beer! Beards! etc.
Tinkerer, Illusionists and pranksters are what I leap to mentally when I first think of a gnome. They do vary a good deal from setting to setting of course. Part of the issue may be that they have varied too much from edition to edition (and other races have more of a through line: honestly though I would need to read all the entries from each edition back to back to really see if that is the case or not). If someone could past in iterations from the core books in different editions I think that would go a long way towards making this conversion more concrete (as it seems there is a vagueness in the discussion now)