I think what looks “professional” will differ by the profession itself and the office environment you’d be working in.
Your current hearing aids might be perfectly, professionally appropriate in some environments, and I don’t want to discount that.
If the job you’re going for is a very “buttoned up” corporate culture, then there might be safer choices in terms of colors. Think about what would be most subdued and something that wouldn’t draw a lot of attention. Matching the color of your hair would be a very safe bet.
I want to be clear that I’m trying to answer your question about what would look most professional. Yes, as some have pointed out, it might be discriminatory for a corporation not to hire you because you need hearing aids and the ones you wear are colorful. I’m not saying whether a corporation should or shouldn’t (or would or wouldn’t) hire you for your hearing aids.
Others have mentioned that hearing aids are like glasses, jewelry, etc - fashion accessories. If we go that route, then there are certain eye wear styles that would be more appropriate in some corporate environments than others and people should make their choices accordingly based on the company and the expectations for employees there.
I wish you the best of success as you consider reentering the workforce. If you do love your hearing aids and the creativity and fun they express, I’d reinforce the message from other posters to look for companies where you and your hearing aids would both be a perfect fit!
Chris