No it’s not widely used. But I think it has a small loyal community. Some people really love it. I’ve only tried it a couple of times, and only on virtual machines. I liked doing admin via text files, and I like that using the “kitchen sink” option you basically have a tool for every task after install. It’s linux but sort unixy or bsd-like in how it approaches some things. That works for some and not so much for others. I might try it out again, but most likely I will stick to Debian.
If you want more software it’s up to you how to do it. With 3rd party tools like sbopkg it’s easier than before, and with tools like flatpak install other software is even easier.
There is also slackware current, and all the other repos, like the work alienbob does to provide plasma desktop etc.
the thing it offers is no systemd, and the mx-linux gui tools to configure your system. Also the advanced hardware support (AHS) is a neat feature. They basically take Debian and make it slightly more user friendly. It’s just less well known than something like ubuntu or mint.