I tried both. Selling small apps is an uphill battle against Apple updates forcing you to buy and recompile. And even if people only paid $1, they will expect professional support. Nowadays, niche apps on iOS don't work financially.
And my experience with releasing useful tools as open source was that companies started linking to them in tutorials, and then their customers sent me unfriendly email and demanded that I provide support for the tool and solve their problems (for free). Most useful open source tools have companies paying the core crew.
For your CV, a video of the app working is probably just as valuable as actually releasing it. And then you can always link to a private copy of the source code in your CV.
EDIT: I focused too much on the negatives at first. What did work well for me was $10/month SaaS and $100+ professional desktop apps. But going there requires lots of polishing, marketing, and I hired support employees.