The most important thing is to make sure the CPU architecture is recent. Especially for AMD, as they tend to re-release very old chips under a new name, so be careful for those! Intel “14th gen” (e.g. Core Ultra 100 series) or AMD Zen 4 is ideal, but Intel 13th gen and AMD Zen 3 is alright for more basic tasks. Newer architectures (Zen 5, Intel Core 200 and 300 series) are probably out of your price range.

Next, you need to look at the CPU itself. An older chip with higher clock speeds will be better than a weaker new chip, though possibly less efficient. A 6-core model is fine for most use cases, but if they do any CPU intensive tasks, a higher tier 8 core might be needed (but is also quite a bit more expensive)

Nearly all the cheap laptops will have 1080p 60Hz LCDs, usually non-touch. For the flippy laptops, it will cost quite a bit more.

Avoid HP laptops, as they are poor value and tend to have worse build quality (+ HP is a terrible company, none of them are great but HP is one of the baddest eggs of the smelly bunch). Dell is a mixed bag due to the sheer number of models they have. Lenovo machines tend to be quite good from my experience (my sibling uses a cheap Lenovo laptop), with good to excellent keyboards. Asus is mixed too, they have pretty good value machines and usually awesome port selection, but their customer service is not great. Acer is usually more affordable than the competition but their build quality is lacking.

Honestly, if I were you, I would go on the used market to find a good deal there.

If you want to check whether the SSD and RAM is upgradeable, search the model number + “teardown”.

And for the OS, go with Linux Mint, Fedora, or similar (any will do, since there will be no Nvidia dGPU issues). Windows will be slower, more privacy-invasive, annoying to use, I’m sure you get the picture.