Any recommendation for an affordable yet powerful laptop for work?

I’ve seen early 2010s mbp on sale for cheap around carousell.

iPad also can if you don’t need to really type ms documents.

I usually recommend people Lenovo ThinkPad if it is for work as you get good value and it's known to be more lasting as compared to other brands

Personally, I would recommend the iPad based on your usage needs. I am heavily reliant on the iPad for my own work, which involves reading of documents and web browsing as well. So far the experience has been rather intuitive, and I do own a bluetooth keyboard and the Pencil as well, and the pencil's great for annotating documents neatly and even you can even use the right apps (highly reco. Goodnotes) to draw mindmaps and take notes easily. Keyboard comes in handy when there's a need to draft longer documents and emails as it is much more comfortable typing on a physical keyboard. The new updated iPadOS even allows you to connect your mouse to aid you, and also to connect external storage such as flash drives as well.

Budget-wise, a basic iPad would set you back by around $500, and you can add on the other accessories over time based on what you need. I timed my purchase of accessories such as the Pencil together with my credit card application, so I manage to get $100 credit to offset the cost, you can check out shopback and moneysmart for such promotions to maximise benefits and discounts while making such purchases as well.
Hope you find a suitable and efficient work companion soon! :)

I would ask you to consider 2nd hand/refurbished laptops. There are a few sellers on Qoo10 that you can consider.

I had the same requirements as you and bought mine for $500 and has served me well for the last 2 years.