You don't need a catalog-perfect home office to work well from home. A handful of things make a real difference; everything past that is personal preference and budget.
Prioritize the chair
If you're going to spend money on one thing, spend it here. You'll sit in it for thousands of hours. A chair that doesn't support your lower back will cost you more in discomfort and lost focus than almost anything else in the room. A secondhand ergonomic chair beats a new decorative one every time.
Get your screen to eye level
Looking down at a laptop screen all day is one of the most common causes of neck and shoulder pain for remote workers. A stack of books under a laptop, or a cheap monitor stand, fixes this for almost nothing. Pair it with an external keyboard and mouse if you can — typing on a laptop that's propped up at eye level is its own kind of ergonomic problem.
Light matters more than people think
A desk facing a window (not into glare, but toward natural light) does more for mood and alertness across a workday than most other setup choices. If natural light isn't available, a daylight-temperature desk lamp is a cheap substitute.
Internet reliability over internet speed
Most remote jobs don't need blazing-fast internet — they need internet that doesn't drop in the middle of a call. If your connection is unreliable, a wired ethernet connection to your router, even just for your main work machine, solves more problems than upgrading your plan.
Noise control, cheaply
A closed door helps more than people expect. After that, a pair of decent over-ear headphones — not necessarily noise-cancelling — does most of the work of blocking out a noisy household or street.
What you can skip
Standing desks, ring lights, multiple monitors, mechanical keyboards — all nice, none of them necessary to do good work. Get the chair, the eye-level screen, and the light right first. Upgrade from there only if you actually feel a gap.