I always remember the Roald Dalh writing chair, where Roald had a custom made board at an angle resting on his chair arms to write. You could make your own like Roald did but the below product is a 21 century version perhaps?
HUANUO Laptop Tray with Cushion, Built in Mouse Pad & Wrist Pad for Notebook up to 17" with Tablet, Pen & Phone Holder https://www.amazon.co.uk/dp/B07NMCQ7CN/ref=cm_sw_r_cp_api_i_80gVEbMSAK893
I found this product very useful
