Having a dedicated app that only handles key management, is ofcourse more secure the putting your nsec key in random websites.
Discussion
Do you have an example? How does the client (e.g. snort) then get the key from said "secure dedicated app"? Snort needs that secret in plain on its own.
A browser extension app, there are many such apps around, I use the Blockcore wallet it has support for Nostr keys but you'll find several around.
The issue is it won't work on mobiles.