Thumb sucking

[Daisydoodle10]

My 15 month old is an avid thumb sucker, she never took a dummy and used breastfeeding for most of her life as a makeshift dummy. she now uses her thumb to self soothe and to get to sleep. I’m aware of the issues it can cause long term with her teeth, but am petrified to do anything about it incase it impacts her sleep.
any ideas of when/how I should do anything about it? Or if there’s anything I can do to replace her thumb?!

I’d do it now as it can affect her teeth.

Have you introduced any other sleep associations?

her routine is book sleeping bag and bed for both naps and bedtime, she didn’t like any like comforters or anything like that

How would you advise I try and stop her?

Just to reassure you, I sucked my thumb to go to sleep until I was about 6 and my teeth have always been fine. So don’t panic too much that it’ll definitely affect her teeth. Also lots of kids suck their thumbs and grow out of it naturally.
Is she only sucking her thumb to get to sleep? If so then she’s not actually sucking her thumb for very long in reality - like 20 minutes to fall asleep or something maybe?
But if she’s doing it during the day too, eg whilst playing or watching tv, then you could intervene by giving her something else to do with her hands. Try giving her a toy she could stroke instead and guiding her hand away from her mouth gently and into the toy or blanket or whatever it is.