I think for your use case, Anytype is good enough, but it’s not FOSS. Obsidian is also not FOSS. I’m not a purist, quite the contrary (in fact I use Notion), but maybe you want to check what’s behind.
Also, to help you make sense of your confusion and take a better decision, you’re comparing a bit apples and oranges.
Some of the tools, like Obsidian, are purely knowledge-management software with some productivity features sticked on top (like kanban visualizations).
Coda, Appflowy and Notion are primarily tools to build software, which can be knowledge-management software, productivity software or other stuff. They operate on a higher level of abstraction and flexibility, but out-of-the-box, for a single user, they are also probably worse than stuff like Obsidian.
You cannot fork or edit the code, it’s just “source-available”.