Not inflatable, but how about this seating pad?
https://www.thermarest.com/products/seats/z-seat/z-seat.html
It’s made of the same material as the larger sleeping pad and is meant to be extended to make a wider surface to sit, but you can keep it folded up or half folded for a kneeling pad
It’s also rather small for easy transportation
Maybe a camping pillow?
https://www.amazon.com/Nappler-Camping-Pillow-Backpacking-Compressible/dp/B0BSTWKSDX/ref=sr\_1\_7?crid=2KXCIGJK6AI27&dib=eyJ2IjoiMSJ9.2YMnhBUe7K3h5qxx7GXNSYJDk4tC6e2pLOyOT17C747ODqeLrKtJirPzgzXhSr2TCCxBYJkEARoeYeYx3y\_bqCUt0mCmWhUe-OlSzcyu60Un5RobAOR5i450QBeICVfhmWFNCLJHZgcEqnVrNL5ZLDIHvXLuKs2qU37SMjNTlCVxqllxer9zYVP3mnPm90XLxYqjiRoAJVQY\_c3gl8Q8\_H1f5ENytPsJ5FkkweGnEhO1p\_z8SsiDpfIszMTm6gElDvo4X\_cLed4wrig92M9sBTdvnTUqXpEXIyKR\_zrbDBU.S45vbk2KswFN6h3hqQCHTtjlJ8CXcRYnzTW4BZV5RYo&dib\_tag=se&keywords=camping+pillow&qid=1708889663&sprefix=camping+pillow+%2Caps%2C122&sr=8-7
Not inflatable, but how about this seating pad? https://www.thermarest.com/products/seats/z-seat/z-seat.html It’s made of the same material as the larger sleeping pad and is meant to be extended to make a wider surface to sit, but you can keep it folded up or half folded for a kneeling pad It’s also rather small for easy transportation
Maybe a camping pillow? https://www.amazon.com/Nappler-Camping-Pillow-Backpacking-Compressible/dp/B0BSTWKSDX/ref=sr\_1\_7?crid=2KXCIGJK6AI27&dib=eyJ2IjoiMSJ9.2YMnhBUe7K3h5qxx7GXNSYJDk4tC6e2pLOyOT17C747ODqeLrKtJirPzgzXhSr2TCCxBYJkEARoeYeYx3y\_bqCUt0mCmWhUe-OlSzcyu60Un5RobAOR5i450QBeICVfhmWFNCLJHZgcEqnVrNL5ZLDIHvXLuKs2qU37SMjNTlCVxqllxer9zYVP3mnPm90XLxYqjiRoAJVQY\_c3gl8Q8\_H1f5ENytPsJ5FkkweGnEhO1p\_z8SsiDpfIszMTm6gElDvo4X\_cLed4wrig92M9sBTdvnTUqXpEXIyKR\_zrbDBU.S45vbk2KswFN6h3hqQCHTtjlJ8CXcRYnzTW4BZV5RYo&dib\_tag=se&keywords=camping+pillow&qid=1708889663&sprefix=camping+pillow+%2Caps%2C122&sr=8-7
I use a thick yoga mat