In Keychain, just do a search for "ssh".
Or you can find it under:
Keychain: Local Items
Name: SSH: /Users/xxxxx/.ssh/id_rsa
You will most likely need to quit and restart Keychain to refresh the list. It helps to sort by Date Modified. You can also try View > Show invisible items.
ssh-add -K will add the key to ...
To be able to install/upgrade a new OS without completely erasing the drive (do you have backups?) you will need to either know the primary administrator account password for the machine, or be able to reset them.
You are going to need physical installer media to be able to reset the passwords, and restoring an InstallESD.dmg file from the bowels of a macOS ...
While it's true that you can't use the keychain in Chrome, I can suggest a solution that I've made.
The explanation involves some web dev, so skip to the end if this is too boring.
The extension has two parts:
The extension itself.
A static website at https://winchpass.com that your iDevice opens.
The extension generates a QR code and you scan it with ...
You can just set a new admin password and then you're able to enter the password for cloning the ESD.dmg file (which you'll then perhaps not even need at all).
You can set a new password by doing the following:
1) Power on the Mac while holding down the Cmd key and the S key
2) When the Mac has booted into single-user mode, type the following commands:
Probably I found an acceptable workaround:
disable the iCloud Keychain (keeping a local copy)
log out and log in again into your User account
re-enable the iCloud Keychain
It seems to work with any need to log out from iCloud and/or loose data.
If I turn off my phone for a few days, would it somehow restart the
password count and I could try a few more times?.
In a word, no. You can try restoring your phone to factory settings using these steps at Apple Support.
If you backed up your device, you can restore your data and settings after restoring your device. If you never backed up your device ...