Yubico - YubiKey 5 NFC - Two-factor authentication USB and NFC security key £48.98 @ Amazon

I’ve bought two yubikeys recently n they work great as I feel more secure. Prior to buying Yubikey I tried google titan usb a and c keys but I could not get them work with windows pc and yahoo so returned n replaced with yubikey usb a and c keys that worked. initial set up for each service and account including generating recovery codes take about 10 minutes. Few things I found are:
1)whilst these keys are considered more secure than digital auth and sms verification, no banks in the UK use it currently so you protect your data for now.
2) PayPal accept ubikeys with PC but not with iPhone mobile app
3) older windows pc may not have new USB C and newer mobile phones do not have the USB A so you may want each type and use other key as a backup if you own an old pc.
4) The yahoo and windows do not allow to delete the other recovery methods like sms or replacement email even after adding ubikeys that negates the full security benefits
5) google allowed me to delete the other recovery methods after adding main and back up ubikeys
6) if you lose the main and back up keys then you will lose your account so please create back up codes during initial set up and keep main and backup in different locations.
7) you will not be able to add the ubikeys from mobile phone for eBay, PayPal or windows and will need to open these accounts from the PC. The option to add keys was visible from mobile but kept crashing for me.
first time set up required me to insert the keys and using NFC to add new keys either took too long for me or was not recognised at all. However after first set up, subsequent use of NFC was fine.
9) I’m rarely asked to use these keys on a day on day and the requirement to use the keys is once about fortnightly mainly on new sites (edited)

I have three for my email incase one dies, no other 2 factor other than a yubikey