On most platforms hashtags are not helpful. Facebook might be the worst that I've seen but I don't do Tik Tok and I'm told that is similar.
I went through a few "reels" and noted common hashtags.
* viralreels
* fbreels
* reels
* videoviral
* reelsfb
* viralreelsfacebook
Non of those anything of value for a user trying to navigate through the the mountain of trash.