I bought ONE youbikey only - Now What?

One of the common question I got about Yubikey is: it is possible to live with only One Key? How should I setup everything to survive the event of losing my only key?
Actually even if this is not a good suggestion, you can happily live with only one key most of the time, lets explore what you need to do and which funcionalities can have problem with the One Key configuration.
Heer Some link for PGP configuration.
- developers.yubico.com/PGP/Imp...
- superuser.com/questions/17216...
- developers.yubico.com/PGP/PGP...
▬ Contents of this video ▬▬▬▬▬▬▬▬▬▬
00:00 - Introduction to Yubikey and Single Key Usage
01:10 - Evaluating the Risks of Using One Yubikey
01:46 - Yubikey Functionalities and Backup Strategies
04:28 - Managing SSH Keys with Yubikey
06:03 - Using Yubikey with FIDO2 or Passwordless Services
08:02 - Handling PGP/GPG Keys with Yubikey
11:10 - Personal Experience and Recommendations for Yubikey Management
12:18 - Conclusion

[@byteme6346]

For using Security keys on iPhone, Apple REQUIRES two physical keys. And I can't get the Nano to work, even with a USB-A to lightning adapter (I've tried two).
I recently bought a Yubikey 5 Nano and a 5Ci. I can register the 5Ci as a security key with my iPhone SE2, but not the Nano. These products are too difficult. I wasted $135.

[@codewrecks]

Apple adapters from usb-A to lightning does not transfer data so yubikey nano does not work :(. This is the problem with proprietary ports like lightning. Luckily enough we should have USB-C for all device now.

[@gilliandonovan4741]

"Promosm"