Basically what you want is to turn the linux laptop into a router. Thats doable. I believe Ars did an article on a similar build a couple years ago.

And here it is: https://arstechnica.com/gadgets/2016/04/the-ars-guide-to-building-a-linux-router-from-scratch/

It's an old build based on an almost 10 year old version of Ubuntu, but quickly glancing through it, I didn't see anything completely out of date. Version numbers will have changed and perhaps some package names will have changed but it will give you a starting point for further research. You won't want to cargo cult this build.

I think the main difference is that your internet would be coming in from the wifi interface and going out the ethernet interface rather than the other way around.