The 1/8" jack on the side is a line output.
Just as a field recorder with the built in mics, the H5 is great, I think. But it’s the only one I’ve ever had so I’m not experienced in this area.
I think using it as an interface is its weakest area. For one thing, I got tired of going through the menu every time to put it into interface mode. Then I would sometimes have to fiddle with closing and re-opening the camera app, and/or exiting and re-entering interface mode to get it to use the interface (this may be more of an iPhone issue, but I had no more trouble when I switched to the MOTU M2). There are 3 interface modes, PC/Mac in bus/battery mode, or “iPad” mode. I really wanted to use bus power so I wouldn’t have to fret about the batteries running out while I was recording, but I never could get it to work, so I stuck with iPad mode.
I think if you’re using your iPad anyway, you’d be better off getting a solid bus-powered interface (like the M2) and using the iPad to record. Use the Zoom for mic recording to SD. As an all-in-one device it didn’t work out for me. Maybe you’ll have better luck but this was my experience and path.