There are plenty of good enough ways:
* For lossless compression of generic data, gzip or zstd.
* For text, documentation, and information without fancy formatting, markdown, which is effectively a plain-text superset.
* For small datasets, blobs, objects, and what not, JSON.
* For larger datasets and durable storage, SQLite3.
Whenever there's text involved, use UTF-8. Whenever there's dates, use ISO8601 format (UTC timezone) or Unix timestamps.
Following these rules will keep you happy 80% of the time.
One format I'm missing: storage for conversations and social media posts. Both are complex media (text + images/videos + metadata), and one is actually a collection of such posts.
How would you go about storing those in a somewhat human-readable format? My goal is to archive my chats and social media activity.