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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
As a separate comment, I also want to mention the existence of Matrix. If Signal is a competitor to WhatsApp/iMessage/texting then Matrix is a competitor to Slack/Teams/IRC. It is designed for federation, but that means you can also host the server yourself. This might be the better tool. There's also a Signal bridge.
I think the crypto firm would need to compromise and switch to Element.io. The app let's you export chats along with other tools like a recorder https://gitlab.com/argit/matrix-recorder/
NOTE:
The number of mentions on this list indicates mentions on common posts plus user suggested alternatives.
Hence, a higher number means a more popular project.