You've seen both routes, hun.
I don't want to lie and say she's a virgin on the love route when she's basically outed herself as a massive perv, is quite capable at blowjobs and used to women going down on her.
It's clear she has some sexual experience but it's not made clear if she is a virgin or not on that route. She deff isn't on the NTR route after letting Pete fuck her in pretty much all her holes.
There are a couple of other virgins so there is still hope but Lydia has lied from day 1 so I wouldn't trust anything she says on either route.
I'd still tell people to play the NTR route even if they had that kink purely because sex dungeon Lydia is more interesting than "I did it, for da porn" Lydia.
Besides, there is only one girl with a name beginning with L that need to be on best girl lists and that's Lyssa.