I think GPG keys get a lot of flack for not being the most user friendly thing and probably fair enough. The nature of them having to remain secret, makes managing them a bit confusing. I don't use mine for anything more than signing commits and (rarely) encrypting secrets

Personally, I use OpenKeychain[1] on Android, Kleopatra[2] on Linux, GPG Suite[3] on macOS and Pass[4] for iOS/iPadOS

Phew, that's a lotta apps but you can just pick and choose whatever you prefer. I have no idea about Windows myself. Once I imported my keys (public + private) into each application, I never really had to touch them again.

As I mentioned, I use my GPG key for signing my commits. I think I saved my password to my laptops keychain so it automatically signs my commits without my interaction.

Similarly, Pass automatically encrypts and decrypts everything without my interaction. Whether that's a good idea security wise aside, it works fairly seamlessly. Pass on my iPad is quite literally just a pull to refresh. I would have thought it'd be much more painful with all the GPG nonsense in play!

So, back to your questions:

> Does your setup require copying the same key to each device?

Yes but only once. It may also require entering your password anywhere from everytime to never depending on your settings. For my android device, I have to do it once every restart but after that, a process keeps my "store" open for example.

> What would happen if someone got your gpg key?

Presumably they could take all of my passwords and sign my Git commits as if they were me.

Personally, I have no strong investment in my GPG key, nor am I someone well known so this would have little to no effect beyond being a big annoyance. I would still own my email account so I'd still be able to reset the majority of my passwords.

Actually, I don't know my email password (since it's randomly generated) so I'd have to cross my fingers and hope the attacker hasn't revoked any of my sessions. Once again, no different than any other password manager. At least losing the key would be my fault, and not that of a third party I suppose.

> What would happen if you lost the key?

Presumably I'd lose all of my passwords but once again, that's no different than the single master password setup of those cloud based password managers.

I didn't realize until I looked it up just now but you can apparently generate a revocation certificate, separate from your key. From what it says on the tin, I imagine you can keep that safe and if you did lose your key, use it to tell any of the popular key servers that it's gone.

That wouldn't do anything to get your password back though, it would just signal to anyone looking up your key, that they shouldn't trust it.

Anyway, that was a bit of a tangent but the best way to learn is to just play around with GPG keys. The only reason I know the little I do is purely through making mistake :) I went through heaps of keys myself (I forget why) before I finally settled on my current one. You can even see some revoked ones here http://keys.gnupg.net/pks/lookup?search=marcus%40thingsima.d...

[1] https://www.openkeychain.org/
[2] https://www.openpgp.org/software/kleopatra/ and https://kde.org/applications/utilities/org.kde.kleopatra
[3] https://gpgtools.org/
[4] https://github.com/mssun/passforios