I went to one of those corporate places for an oil change ... This fell off sometime on my drive home from work.
Exact same thing happened to me. Ever since then, I do my own oil changes.
Although, there's definitely a startup cost. If you're tight on cash, then I wouldn't recommend it.
I guess the splash shield isn't essential for driving... although, you should probably get it back on at some point. It'll keep the elements out of the engine a bit. Getting water down there will probably lead to corrosion in the future. Not to mention rocks that could dent things down there.
It shouldn't actually be too hard to put it back on. It's usually just held on by plastic screws. You just need to buy replacement screws (a few bucks) and find a screw driver. The hard part would be lifting the car high enough so you can crawl under it. Then just line up the holes and put the screws on.
The Ratta Supernote A6X2 Nomad is 329USD, cheaper than the devices you found. The A5X2 (bigger) is 505USD though.
Devices I've owned:
I currently own the Supernote A6X2 and I'm super happy with it. I use it almost every day to diagram stuff for programming. I also read technical books on it. The Supernote A5X (the previous version) was also very good. I just ended up liking the smaller size better.
My favorite feature is that Supernote does NOT require a subscription! The device also has plenty of other features. You can read PDFs and ebooks, of course. You can even install the Kindle app on it, though you can't install any Play Store app. The palm blocking is good. There are gestures to help you write faster. There's a shape tool. Different pencil sizes, highlighters. Paper backgrounds. Hand writing recognition. And you don't need to buy replacement pen tips!
Supernote cons vs reMarkable: