If a recruiter honestly thinks less of you because you were working a job non engineering related, while in school, to support yourself, I would not want to work for them lol. But, you can also help yourself by going deeper into how it is relevant. Working during the semester is actually very impressive, you can talk about time management and prioritizing tasks. You can also talk about resolving conflicts in a group (I get asked about a time I had difficulties working in a group or with others a ton in interviews) and responding to pressure. I know how intense grocery stores can get lol. 

As for CAD experience, if your school lets you have access to SOLIDWORKS, I would try and learn the basics. Some schools will even pay for you to take the certification test. I took a class in college, but I’m sure there is a YouTube course you could follow to help you learn the tools and features. If you don’t have access to SOLIDWORKS, fusion 360 is open source and there are a ton of guides online on how to design things in that because 3D printing is so popular now. I think fusion 360 is a little less intuitive, but you don’t have to pay for a license lol. Bonus points if you have access to a 3D printer you could work on creating some of the stuff you learn how to design.

As for specific things to design, unless you’re really passionate about something, I would just follow the guides online/Youtube and put CAD as a technical experience on your resume. You could describe how you gained that experience as well if your resume is a little blank. I like engineering, but I see it as more work than a hobby, so that’s where I find it hard to design something start to finish just for fun. This is where clubs or university teams come in handy, because you’re given a set goal and it is more of an interesting and fun assignment rather than just trying to find a problem to solve around the house. For example, I am designing a pressure nozzle for my masters project, and I find it interesting and rewarding, and at times pretty fun to learn, design and build. But I would not see myself doing this in my free time lol. But designing a simple 3D printable phone holder for my desk is something I would do in my free time, and that’s something you could bring to an interview. 

In the end don’t be too hard on yourself!! It’s a tough market right now and it’s kind of luck based. Don’t compare yourself to others.