Similarly, I'd stopped playing computer games as I couldn't be bothered/find the time to go and use my desktop windows PC. As soon as the Steam Deck was announced, I put my deposit down, but was a way down the queue. However, I was on holiday when I reached the front of the queue and missed the notification, but instead saw the refund three days later of my deposit! Somewhat annoyed, I paid the deposit again and joined the back of the queue, but luckily they were ramping up production and I didn't have to wait too long.
It's the sheer convenience of it that makes it a winner. You can just pause/resume it and even just play a bit of a game during a TV ad break. It's great for exploring old, unplayed games from my Steam collection.
Now, if I can just figure out how to enter a cheat code to get me past a Half-Life 2 save point (in Ravenholm) where I don't have enough health (or more likely skill) to survive.