Creating nostr keys on any old app and then plugging that nsec into other apps is a way to get your keys compromised.

Best to use a bunker. Amber keeps your nsec secire and signs in to other apps. Creating keys in Amber and never using nsec in other apps is best.

You can use an android device as a signer for nostr desktop clients too for exmaple.

Compatibility with the best bunker is repsect for user keys.