Personally, I’d really want PC Fey to at least share in their NPC race cousins‘ nature.
This makes me rethink the Elf "fey ancestry". None of the fey have resistance to charm, so it is unclear why being a descendant would gain it.
By contrast, fey typically have Magic Resistance, as well as Innate Spellcasting. Thus the fey type and the fey ancestry should probably look more like these.
Magic Resistance. You have advantage on saving throws against spells and other magical effects.
Of course, Magic Resistance is powerful, but it only applies to magic that allows a saving throw. No-save magic hits normally. The Magic Resistance trait can divide up into three traits, depending on the save ability: Int-Wis-Cha, Str-Con, and Dex.
Note the Gnome Cunning grants advantage against magic that allows a mental Int-Wis-Cha save. The Gnome is quite fey in this way. Perhaps other traits at a higher levels can expand this fey Magic Resistance to include Con and Strength. Later even Dex.
Likewise, the Forest Gnome has Natural Illusionist, which is something like an innate spellcasting, and again typically a fey trait.
For the Drow, the Magic Resistance fey type trait might start with Magic Resistance versus Dex save magic.