I’m using the Gnome Keyring on my Arch Linux system with Xfce desktop environment, and access its secrets from the command line with secret-tool, but I believe KeepassXC also supports the DBus Secret Service API, so that you can use secret-tool with it also.

Callcentric has Canada numbers. For their Pay Per Minute plan, there is a US$3.95 setup fee. Monthly charge of $3 for the number, plus $0.015 per minute incoming voice (outgoing charge varies by location called) and $0.01 per SMS. Probably an additional charge for 911 emergency number access if you tell them you are going to use the number from inside the USA or Canada.

You can read your text messages on their website and/or have them sent to your email address.

I got a California number from them when I was living there in 2009 or so, and added the SMS more recently (which added $1 to my previous monthly charge of $2). It has never failed me for SMS verification for banks, etc. I have not tried WhatsApp or Telegram.