First of all, the silicone-free shampoo that you mentioned is actually a marketing scam created by individual manufacturers. Experts from national regulatory agencies have issued a message expressing the hope that manufacturers will be able to self-discipline and avoid excessive consumption of the concept of “silicone free”. This is why the international big-name follow-up is so slow.

Silicone oil in shampoos, if used normally, does not impose an additional burden on the hair. Correspondingly, those silicone-free shampoos will also add some cationic conditioning agents to achieve a similar conditioning effect in order to achieve a similar post-washing effect.
Speaking of skin care products, silicone oil is added to skin care products for two purposes: to adjust the feeling of use and to seal skin care. Silicone oil (especially polydimethylsiloxane), due to its innate characteristics, can improve the smoothness of the skin, reduce the stickiness and enhance the pleasure of use. You don't want to be sticky on your face after using it, it's easy to get rid of it. Secondly, polydimethylsiloxane is a fairly safe and stable raw material, and it is also found in breast fillers and condom lubricants. They stay on the surface of the skin and can be used to seal off water, long-lasting moisturizing, and wind and dust proof.

So you still think that silicone oil in skin care products is superfluous?
Whether polydimethylsiloxane is safe for sunscreen products and whether pregnant women are available. I will answer in detail:
Polydimethylsiloxane is a very safe, stable and inert raw material from the structural point of view. It is used in a very wide range of fields depending on the degree of polymerization. In the field of daily life, it includes breast augmentation prosthesis and condom lubricant.