My SD has just turned 10 and is going into year 6 in September, however for the 18 months her hair has been getting pretty greasy and she's been getting spots/blackheads more recently.
For her birthday I got her a Byoma skincare set, she was absolutely thrilled with it. I really like their branding ethos, which seems to be 'clean, not perfect'.
I don't think it's ever too early to learn how to clean your face and protect your moisture barrier properly!
I think if SD was 'my own' and/or lived here more often we would have started it when she was 8ish, so when she actually showed signs of puberty she would know what to do and already be on top of it.
So maybe start with basic skincare and haircare education.
The silk or satin pillowcase someone else suggested is a nice shout, too. The mulberry silk ones are the best, but the Kitsch brand satin pillowcases are more affordable and decent enough for entry level lux pillowcases.
A body lotion/moisturiser could be a good idea, you can teach her about scent layering with body sprays (the non aerosol ones). No point using a body spray without a decent lotion or moisturised layer for it to cling to, even better if it's a scented moisturiser.
If she doesn't need deodorant, she can still smell nice!
Also, SPF. Another vote for Byoma.
All of this is hygiene and hygiene-adjacent, not really hyperconsumercore stuff.