I haven’t done a jig saw in probably 30 years. I can understand it, I think.
To each their own.
The best answer is to find a way they can do their puzzles. The tray looks cool. But really a self service tray like at fast food joints seems like it would work just as well.
Except those trays are about half as big as a regular puzzle. So no.
Another free on-line option. I don’t know whether it will appeal or not, but it’s painless to give it a try.
Surely there’s smaller puzzles.
Rubik’s Cube
A larger or smaller puzzle isn’t just more or less of the same thing. The experience varies depending on the size. For any type of puzzle, there’s a size that’s more fun than other sizes. Smaller puzzles are generally dull, and larger ones tedious. It’s obviously not exact, but most people who do puzzles have preferred brands and sizes.
Any chance of her enjoying the novelty of trying something new, like maybe knitting? That’s an easy bed- or recliner-bound activity, and cheap “entry point” e.g. not a lot of upfront investment if she decides, “naahhhh.”
I think something with (possibly foldable) legs would be better. A flat tray is too easy to spill.
Honestly, something more like the one linked upthread seems nice, and versatile for things like meals or tablet browsing.
This may not work for the OP’s purposes, but I’m going to file it away for the next time I need something similar to give. I could see a beginner “knit a scarf” or “crochet a doily” or “latch-hook a rug” kit.
I play solitaire on an old Ouija board. Unless you have boisterous dogs or kids jumping around, an adult can keep a board still on a lap.
Lap boards are everywhere and not $70.
Do the spirits help you?
My mother loved jigsaws, but if they were impractical, such as while travelling, she would turn to crossword puzzles. She (and I) preferred NYT Sunday puzzles, but neither of us would turn up our noses at Penny Press/Dell collections if they were the only things available at the airport newsstand.
The one I mentioned is Microsoft Jigsaw - the Microsoft Store has it, and it is free, with ads, but not obnoxious ads. I play it on my laptop, but it is shown on tablets also. I not only have and do tons of puzzles, I got consulted on puzzle complexity for Sister Boniface. If it doesn’t bore me, it won’t bore anyone.
My wife had two knee replacements, so I feel for you. She recovered quickly but lots of people we know took much longer.
Cursed things lie alot.
Hey don’t they make roll up mats for jigsaw-ers.
Speaking as a jigsaw puzzle fan, i have no idea what else she’d like to do. I like to do nonograms on my phone. Maybe that’s like doing jigsaws? I also like to play Minecraft, but that feels different to me. I’ve tried computer “jigsaw puzzles” and they do nothing for me.
Maybe set her up with books and videogames she likes?
I found a “paint with stickers” book on Amazon.
Very cheap.
Seemed puzzle like. Not childish or coloring book style. It was for adults.
Just search “paint with stickers”.
ISWYDT 
Brain Games is one name of a publisher that does very nice paint by stickers books, as well as word searches and other puzzles. Good quality. Amazon has scads of them.
Those look interesting. And pretty reasonably priced. I’ll give them a try.
Yay. I was helpful