Hi @xin-li, I have been having this same problem since 2016 and am now trying to solve it. Let's try together! Ergonomics is very important, I agree. My back pain is a problem too.
I have used a very old drafting table and didn't like the instability of the table and the slant causing items to roll off, but modern tables have much better features and design.
I have used a wooden tabletop easel similar to the ones in your links. I think they're OK but they didn't work for me for reasons that are specific to my traditional medium (colored pencil and pan pastels on drafting film which is transparent). They can be great for "plein air" painting outdoors and some have a drawer with storage for supplies, and a handle to carry them!
I needed a white smooth surface so I purchased this one and so far am happy with the ergonomic improvement and design features. They say there is science to show that this angle is ideal, but artists do well with a variety of angles while working.
But the biggest tip I can offer is to try to modify your studio setup with whatever you have available that produces better posture based on best practices. So I'm using pillows behind my back, and a yoga mat rolled up under my feet as a foot stool, things that can help me achieve better posture until we can afford to remodel and make room for an actual desk and actual chair. Currently, I have to work at the kitchen table and sit upon a cushion placed on top of a wooden box filled with solar batteries for our off-grid tiny house electricity system. It's a messy solution but I hope it helps.