I have heard of Ryan for a girl. Can’t remember where, but think it must have been an American tv program. I don’t like it all that much. Don’t hate it though.
Maxwell and Ruaridh are Scottish boy names to me, so I’d find it quite surprising to meet a Scottish girl with either of those names tbh. My friend is Frances (she goes by something else now) and she hates her name as people always thought she’d be a boy when she was introduced.
I like names which can be unisex, like Evelyn, Kelly, Robin and Rowan or longer girl names which can be shortened to something more boyish;
Leonora - Leo
Aurora - Rory
Georgiana - George
Alexandra - Alex
Harriet - Harry
If you’re set on Max for short, then maybe Maxine, (I don’t really like it tbh, but you might).
I quite like the ‘surnames-as-first-names’ thing for girls though. I actually prefer it for girls than boys for some reason. They aren’t traditionally ‘boy’ or ‘girl’ names anyway, so they’re fair game for either imo.
The thing about wanting to pick a unisex / gender neutral name is that it always seems to be girls being called traditionally male names ime. You never hear of boys being called girl names.