I was gonna go to sleep before having a spergout about troons after finding some low effort troon (a story for itself), but one that does make good content and fortunately I found something else to respond to at 4:30 in the morning.
Laptops aren't necessarily garbage, and they can be pretty practical if you want to be on the move. You can even turn one into a portable TV VCR combo unit (The HDD/SSD being the recording media) with a TV tuner USB stick, if that's your thing, if it has good enough battery life to make it worthwhile. They are much more practical than even some really smol ITX form factor PC transportability wise. However, maintenance IS a pain in the ass for them compared to desktops. And at the OP's price range, you ain't gonna find a laptop that's of decent specs AND of decent enough battery life, even used!
When I saw the title, I was assuming something in the low 4 digit range, as that's when you start finding pretty decent specced laptops at least in some way for the money. But, at 300 USD you might as well just get some used Optiplex type of PC and upgrade it where possible, or get an Android tablet. But, if you wish some laptop, I guess just get some at least i5 equipped normie type of used laptop and put an SSD inside of it. One of the best ways to upgrade old laptops is an SSD. Even dinosaur XP era laptops benefit from it!