I know you deleted your comment, but you’ve already started on the right track just by asking questions. This is the first step to getting something that gives you both control and convenience.
Ask a friend with the know-how, ask a forum member, ask a search engine, etc.
For instance, when it comes to software, websites like alternativeto.net, and slant.co can help a lot. If privacy or security are what you seek, then you can use more privacy-oriented websites like https://www.techlore.tech or https://www.privacytools.io.
Understand, however, that striking a balance between privacy/security and convenience is not usually a priority for the best/top tools in each industry. For instance, Obsidian is likely the best tool out there due to its extensibility and platform availability, but it’s closed-source. That being said, if you are very serious about privacy/security, you could actually lock down Obsidian the same way you can lock down a web browser.
To do this, you’ll need to use a firewall implementation like firewalld, ufw, or portmaster. In addition to this, you’ll need to download the new updates to Obsidian (or another app) directly from their website and replace your existing one. This is way less convenient than just having the app auto-update each time it launches, but at least you can guarantee that no information is being sent to their servers or anywhere else.
In doing all that, you’d have the inconvenience of updating apps the W1nd0ws way, but the convenience of having an app that can do a whole lot. And of course, you’d fully control all your data.
Another method of course, is to use the free and open-source apps that are provided by the Official distro repos. Not enough for me, but is enough for lots of users.