After thinking about getting my own domain name for a while and letting the thought rest for a couple of months, I finally bought one. It is a very easy and inexpensive process, and I am happy I did it. The original idea was to set up my email with it, so I could change my email provider without changing the address (I am in the process of changing my provider, and it takes a lot of effort), but having a domain name opens a world of opportunities.
Although I had known about how to get a domain for a while, I didn't have much experience on which companies were "better" or "worse" (since I only needed a domain but no hosting, I am not sure why a company could give me a more appealing offer, since prices are the same in all websites). I finally decided to go with Gandi.net because a known site uses it, I had heard about it on the Fediverse, and it looked like a good and reliable company. The hardest part was figuring out which domain I wanted, once that was decided, buying it took around 5 minutes.
Since I had never seen a DNS record before, configuring my email provider was a little trickier. My provider gave me some lines to copy and paste into the record, but they needed some modification in order to work, so it took me a little while to figure it out. The next part was setting a landing page for my domain: if someone saw my email address and wanted to check what obenedito.org was all about, I didn't want them to get a 404. So I designed a very simple page with my name and a link to my email address and one to my GitLab account. Since I don't have a home server or a VPS, I decided to host my page on GitLab (basically because it's free and I don't need a dynamic website). I once again had some trouble setting up the GitLab custom domain—the lines I was given to add to the record weren't the ones I actually needed to add, so that took a bit to figure out as well.
I still have a lot to learn about how DNS records work (for instance the difference between a type A or CNAME entry), but, for now, it works just fine.
Edit: My personal domain has been moved to oscarbenedito.com.