Concerts are a great alone activity. You can just blend into the crowd and are continuously entertained once it starts. Just try it. It is really not awkward at all.
Tried going to a smol festival alone last year. Didn't like it. It was only one stage and it got really boring between the bands. The crowd is less into the bands because they don't come just to see the band and more drunk bydlos. Also I lose all my urge to see live music after 3 hours or so. I don't need any more for the day and especially not for a couple of days in a row.