
Should I use a cover letter to explain my employment gap?
I've been looking for a job for almost a year now but I've been busy with other productive activities that might help me stand out if I can somehow include the info with my resume & application.

The cover letter is not for that purpose. When you go to the interview they will ask , or some application might have a section you could do that. Google Cover Letter and it will explain the purpose of one.

I would even though I didnt do that on this previous aplication, but I did get hired. Im very excited.

You can also say that you were contracting....That's the "double-edge" sword of being a contractor: looking like you're job-hopping or having gaps in between jobs. Just say, "I took a break, achieved something on my bucket list".....

In some circumstances, it is also a good idea not to put dates of the beginning and ending of a job on a resume

Add a Volunteer section to your resume. Name of charity - dates - and activities. awards or recognition if any

Hi Jeff, I would definitely include the other activities you have been doing in the last year to show that you have been productive. I think you can include it in your cover letter as long as you are brief and clear. That way if it is asked in an interview, you have more room to elaborate.
What I do in this situation is draft the cover letter, explaining my achievements, my skill set, and how I can contribute to the position I'm applying for. Then I have a recruiter or college professor review my cover letter for applicability to the position I'm applying for before I send the cover letter to the hiring manager. Always have someone in the industry like recruiters, job coaches or professors review your work before submitting it. Best of luck to you.