I'm not familiar with the current generation of dating apps, but I met my wife on plentyoffish a few years ago. I also was a lonely introvert and provide my experience as an example to the OP:
I was in a very similar situation to the OP, an introvert who's career and interest led to a state of near constant solitude. I lived this way for over 10 years. I had a weekly routine; weekend was going to the store and househould maintenance, weekdays were going to work and fiddling with side projects after work. I would visit family every few months. But otherwise I was entirely alone. I feel that I am a true introvert, and relished it for few years, but it ground on me. Later I realized that I could die and no one would know for weeks. This was profoundly saddening to me.
I used online dating off and on for years with no success, and a lot of frustration as the parent indicates. It can be crushing to message 20 women and get zero responses. Over the years I worked on tweaking a message (a/b testing essentially) to see what would get responses, got some flattering photos to use. Then after I started getting some responses, and going on a few dates, still nothing. At one point I gave up for good, decided I was asexual and unlovable, and resolved to live out my life alone.
I won't say I was ever depressed, I do have a melancholy disposition. I experienced one episode of real depression for maybe a day, it was a dark pit, I couldn't stand to live. Luckily it only lasted a day, and never returned. That episode showed me how bad depression can really be. Not a constant state of being down or blue, but grinding darkness that makes your own skin unbearable. It was terrifying.
What drove me out of all this was series of illnesses with my parents. I had always imagined I'd get married have kids, but had zero success dating. I realized if I ever had kids, they wouldn't know my parents if I didn't act. So I got back on the horse, systematically used plentyoffish to date a lot (edit; well, less than 10 so not a lot) of girls and eventually met my wife and we have two kids.
Nowadays, I'm happier than I've ever been, but things aren't perfect. Being married is hard, particularly since my wife and I were both older when we met and "set in our ways". She's not the easiest person to live and neither am I. Our kids are a joy though. I get zero alone time now, which also grates on me. I REALLY need it, and my spouse is not sympathetic.
My wife says about herself "I was lonely wierdo, until I met you, now I'm not lonely, just wierd", which also applies to me, which amuses us.
Anyway all that's my .02, you're not alone, and that was my path.