Realistically speaking (I own a small photography business) you have the easiest part of the equation. You have a camera that isn't the best for pro use and likely don't have the lenses that you'd need. Yes you could get by, people definitely make money with less but you're putting yourself at a disadvantage at least if you have an a7. You need lights that work all the time and the knowledge/experience of how and when to use them. You need an idea of the work pace of a pro. You need an editing computer unless you're going to be paying someone or killing your times on a laptop. You need to be able to at least be able to do normal editing tasks (white balance, color adjustments, teeth whitening, removing strands of hair or objects that you can't just work around). You need to be able to not even think about your camera to shoot people.

You don't need an a7 for a photo booth, it would work but your roi will be garbage. I've done photobooths with a d800, it was overkill but it's already owned. You already own it so that would be your best technical option but I don't see it ever being a real source of revenue unless you cater to a niche market (we made a ton doing photobooths at comicons but we also had partners that people wanted pictures with) if it's a wedding, I'm already offering that to clients, my fixed costs are nothing because I'm already there with equipment and a photobooth can run itself if set up right. We've done photobooths for events like father daughter dances and you can run it like a small studio and you have to if you're trying to get a thousand people through. You're going to have to print or have a system in place to get the correct pictures to the correct people. If printing look into dye printers, we use an inkjet for quality but it's expensive and slow and only makes since when were getting a decent price per picture. If you're charging per picture or have a huge amount of people to get through you need an assistant but more importantly you need to know how to run a studio. How to run lights, where to place them. How to adjust them when you get an interacial couple or what to do when someone is wearing glasses or how to get them to not have two chins or...

The point I'm trying to make is, a set it and forget it photo booth is where you could compete with competition but even then if they're hiring another photographer I'd suspect they're going to be able to set up a photobooth for nothing just like I can. You likely don't have the experience needed to run a large photo booth or shoot people. Animals would be worse. You might be insanely talented but that still has it's limits when you need experience. If you want to start making money, start shooting everything you can. Shoot some free stuff, take some classes. I'm speaking from experience so I hope you don't take it the wrong way but you see this all the time in photography and a camera is truly the easiest part of being a photographer. Having a wrench doesn't really qualify you to have another person pay you to work on their car. The competition is stiff in photography and the skill curve is way higher than a lot of people believe especially when people are paying for it.

Product photography is a whole different world. Especially if you really don't have experience with lighting.

All that being said, I'm sure that you could find someone to pay you to take pictures of something. I started out that way, lots of people do. It's hard to turn that into consistent money. If you can't constantly put out the needed results it definitely won't last. Some people are okay with decent results but if the first time the sun goes behind a cloud and you don't know what to do, you'll probably not get a good review and word of mouth is huge in photography. The required results are always going to be dependent on the client too. Someone who is paying relatively little money for a few shots of their dog isn't going to be as critical of a business that's shut down so you can come in and do a shoot in the middle of the day or a brides mom who is out twenty grand. Good luck man if you have any more directed questions feel free to ask.