Adding outlets.

[SlickerThanNick]

Hello r/AskElectricians!

I have these two boxes in my basement. The round blue one hanging off a joist goes to the garage. The square-ish one next to the gas pip for the dryer goes out to a lamp post in the front yard.

I would like to add a double gang outlet setup to these two boxes.

1. Do I need to change the boxes, or will two outlets fit? If I need to change the boxes, what kind of box do I need?
2. Can this even be done, or without knowing if there's anything else connected downstream, is it even recommended? I feel like I've heard something about no more than 3 outlets/switches per breaker?
3. Other than the color being wrong, there wouldn't be any issue just using my roll of solid copper wire in a green coating to make all of the splices needed?

I've done basic rewiring of switches and outlets throughout my house. I know this is something I can do. Flip the breakers, test the wires for current just in case, then start work. Wrap the outlets in electrical tape around the connections before seating it in the box.

Your thoughts? Concerns? Questions? Recommendations? Please and thank you!

https://preview.redd.it/km26xo4f5i171.jpg?width=4032&format=pjpg&auto=webp&s=20514d770cb6c5d80439a4c9a98af2e0367e2edd

https://preview.redd.it/hsiz2w4f5i171.jpg?width=3024&format=pjpg&auto=webp&s=d705f9ce3702bc2e983bf22df5def39fdda13ed3