We are going to add Notion like features to Baserow in 2022. You should then be able to create similar documents within the same tool and it is going to work well together with the databases and tables that you already have.

You can try us out when we launch, though for us it is more "assemble your own Notion tool like Lego" rather than an out-of-the-box Notion clone.

Check out anytype.io

This sounds a lot like getoutline.com