Volunteering is a good idea. It doesn’t need to be in a group or physically hard. Serving meals in a soup kitchen etc It’s a good way to help others, make yourself feel good and maybe make some friends.
I honestly don’t think meeting new friends online would work unless maybe they are pursuing same hobby or it’s a site for shared interests. If it’s just random people (and by random I mean you know nothing about them), then there’s no foundation and it’s very unlikely to work in a long run