After trying many note taking apps I am liking the CherryTree software. Linux/Windows/$0
I like the look and feel.
Control-Shift F is the best way to search within your files. Once I used that instead of just Control-F I was 100% happy with it.
Data files not in the cloud.
I was in a similar situation many years ago. I was using Ecco Pro on Windows but then had to move to Linux. When I first looked at CherryTree, it was a shaky Python/GTK app; meanwhile it was re-written in C++, which likely improved stability. My conclusion at the time was to build an application myself in a stable technology which improves over Ecco Pro; the resulting CrossLine proved to be stable and useful for all sizes of projects since.