Histdb is amazing, but requires zsh. I have one continuous history. I'm working on figuring out multi-host history for One True History.

https://github.com/larkery/zsh-histdb

I haven't tried it, but the keywords you are looking for is bash history db/sqlite. E.g.:

https://github.com/thenewwazoo/bash-history-sqlite/blob/mast...