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Phone

Android — Termux.
Install Termux, install OpenSSH, then run the same Bash commands as on a PC:
pkg install openssh
curl -O https://raw.githubusercontent.com/mymyanmarland/vps-connect/main/connect-vps.sh
./connect-vps.sh --name vps2 --host <VPS-IP>
ssh vps2
One run per device.
Run the script once on each device you want to use. Each device gets its own key; the VPS accepts all of them. For a new VPS, run it again with a new name and IP.
iOS has no full Bash terminal like Termux. Use a PC terminal for the first setup, or an iOS SSH app with its own key import. The alias itself lives in ~/.ssh/config on the terminal where you ran the script.