I would ask what you are aiming to do.
If it is compare pillows then it should be noted the pillow and mattress world is one massive scam really and everybody has different names (and wildly different prices) for things that come from the same factory. This can make comparisons hard, which is kind of the whole point of the scam.
Likewise enough will blend it with their own herbs and spices that the name of some elastomer (many of which are trade names themselves, elastomer being the name of a category of plastics/polymers that behave like elastic as opposed to hard shells like many day to day plastics) and maybe a process might not cut it for your purposes (or at least be the start of an engineering project and many tests). The texture they put on it is also not accidental; the texture likely being there to prevent slipping and also some kind of minor air cushion lest sweaty skin get in complete contact with it and it feel nasty when it peels off.
A lot of the "gel" substances they sell to normal people are not going to be able to be moulded by heat so be aware of that one if you do need to consider a texture, though TPE resin probably could be (thermoplastic polyurethane elastomer, urethane rubber also being a good search term.
https://www.benam.co.uk/products/urethane being one such example, you will find similar in more specialised building trades and model making as well) and is a likely candidate for many of the things showcased, as might silicone (though that gets very expensive if you are going to buy a bucket or enough tubes to do some real damage compared to urethane based efforts).
I have seen similar materials used in door mats, shower mats, anti fatigue mats, cooling mats and similar such items. Though they likely use a slightly different durometer (hardness for plastics as it does not work quite the same way as metals and many other materials) of it than I would likely stick on a pillow if you were planning to harvest some for your purposes.
If you can get one in your hands it might also have a safety sheet and/or a recycling sheet that would indicate what materials are used in its construction.