I'm not sure how relevant my experiences are, as I have (sadly) never done a solo trip and I'm also someone who loves time alone (I'm a mom of littles so alone time sounds like heaven these days).
On our last trip to WDW, I found myself semi-alone quite a bit (ie, wandering alone with my sleeping toddler in the stroller while husband took our other kiddo on rides or whatever). Since we also did not fully understand rider swap at the time, I rode alone on quite a few attractions. I never once felt like anyone - guests or CMs - treated me any differently than they did when I was with my group. I sat down at several places for a drink/snack while toddler slept. While I might not say that tons of people were "supportive" (because I'm not actually sure what that would entail), no one ever bothered me, or looked at me sideways that I noticed (granted, I know I wasn't technically alone, but I did FEEL alone as I had no one to talk to). Since I was tied to the stroller, I killed a lot of time seeking out photo pass locations and I took lots of photo pass photos either on my own or next to a stroller with the shade pulled down
I felt a little funny about that at first just bc I'm not someone who typically takes pictures of myself alone, but the CM's were unfailingly fun, encouraging, kind and friendly.
On the occasions that I WAS actually alone, I honestly didn't feel like anybody thought anything of it, if they even noticed at all. When I was young and single and most of my friends were already married, I did lots of things locally, solo - including going out to eat, the movies, sitting at the bar, etc. I felt like more people thought it was weird when I did THOSE things than anyone did in WDW. In WDW, it's super common for guests to be solo for various reasons, and no one blinks an eye. We once had dinner at Biergarten with a really wonderful young woman who was solo for dinner because the rest of her group wanted to eat somewhere else, but she was dead set on Biergarten. Like me, parents are often solo in WDW for various reasons. My own mom was solo a lot on our last trip because my dad couldn't join her for health reasons, and she wasn't up for being in the parks as much as we were with our young kids. Point being, I never have made assumptions about solo guests in WDW, and I don't feel like anyone has ever really made any assumptions about me when I've been solo in WDW, however briefly.
If you don't want to do WDW solo because you're afraid you'll be lonely, or because you think you'll feel awkward, then there's nothing wrong with that. But I wouldn't not go out of fear of being judged. Because first of all, if anyone judges you, then that's a them problem, not a you problem. And secondly, I just don't think anyone is actually judging