It's funny that you posted this, as I've been wondering if a curling iron might help with my fine, but also thinning hair. I'm letting it grow out a bit so it's in that awkward stage, but I just had some layers put in. I don't know if I can strategically place the crimps so that they're not visible, but for $20, it's probably worth some experimentation. I've found a few styling products that help (Bumble & Bumble Thickening Hairspray and Phyto Phytovolume Actif), but most anything I add to my hair really weighs it down. And I just hate product in my hair anyway.

If you're talking about a TV commercial.......really pay heed to mimi's post and adjust your expectations.

Sorry, I've got no input on serums, but I just wanted to say that I bought a new hair dryer, and my hair has been so much smoother! I had followed a previous thread here about hairdryers and wanted to buy the Rusk that was highly rated, but it was no longer available. So, after Christmas I was in Costco, and they had a T3 hairdryer on sale. I bought it and I was surprised that it actually does dry my hair faster, and my hair is and remains smoother. I really never believed that these expensive hairdryers made a difference, but apparently I was wrong. After I dry my hair I briefly run a straightening iron through it - much less than in the past, and then my hair stays smooth for several days until my next shampoo.

NYT recently had an article on hair loss and how minoxidil at very low doses taken orally seems to work well: https://www.nytimes.com/2022/08/18/health/minoxidil-hair-loss-pills.html?searchResultPosition=5 "But there is a cheap treatment, he and other dermatologists say, costing pennies a day, that restores hair in many patients. It is minoxidil, an old and well-known hair-loss treatment drug used in a very different way. Rather than being applied directly to the scalp, it is being prescribed in very low-dose pills. Although a growing group of dermatologists is offering low-dose minoxidil pills, the treatment remains relatively unknown to most patients and many doctors. It has not been approved by the Food and Drug Administration for this purpose and so is prescribed off-label — a common practice in dermatology.... Dr. Rodney Sinclair, a professor of dermatology at the University of Melbourne in Australia, had a patient with female pattern baldness. The hair on top of her head had thinned, and she hated the way it looked. Unlike what happened with most of his patients, Rogaine worked for her, but she developed an allergic rash on her scalp from the drug. Yet if she stopped taking it, her hair would thin again. “So I was stuck,” Dr. Sinclair said. “The patient was very motivated, and the one thing we knew was that if a patient has an allergy to a topically applied medicine, one way to desensitize is to give very low doses orally.” To do that, Dr. Sinclair tried cutting minoxidil pills into quarters. To his surprise, the low dose made her hair grow but did not affect her blood pressure, the original purpose of the higher-dose drug. He subsequently lowered the dose more and more until he got down to effective doses of one-fortieth of a pill and began routinely prescribing the drug. That first patient still takes it."