You can try without doing an intake port, as you said you have a vent open from what I'm assuming is the heating system. Either way I think a bathroom box fan is an easy solution here, you can tinker with the rest.

As others said the big thing is getting a larger volume of air moving. A quick Google shows an electric air pump moves about 20 CFM where a cheap bathroom fan does around 50 or more. So triple, ish.

Someone else in the comments already did the math for how long it takes to clear a room with different CFMs but I think it's pretty clear an electric air pump is just not gonna cut it.

What's your budget for improvements? I'm thinking you could replace this whole set up for about $100 or less. Get a bathroom box fan 50-100 cfm and some more flexible ducting, run the ducting and fan close to the work surface/farther end of the room from the window, and then create another hole in your window setup to allow air in (same size ad your output hole)

I get the impression from your comment though that you're maybe looking to spend 0$? I think it's worth the small investment to save your health.

OP I've literally done this and it works very well, super solid and not noticeable. You could even paint it if the raw wood look bothers you but no one will see it.