Anytype looks interesting but it looks like most of it is non-free non-opensource software:
While our core solutions, the infrastructure protocol any-sync, and the data protocol any-block, are released as open source under the permissive MIT license, we distribute the remaining layers, including the middleware library any-heart, and applications like anytype-js, anytype-swift, and anytype-kotlin, under the Any Source Available License. This license grants individuals the freedom to review, modify, and utilize the code for personal, academic, scientific, research, and development purposes. However, for commercial use, consent from the Any Association is required.