You can have KDE Wallet unlock automatically when logging into KDE Plasma through GDM. The preferred method is PAM: GDM passes your login password to pam_kwallet5, which unlocks the default kdewallet. KDE’s documentation confirms this is the intended mechanism. (Arch Linux Wiki)

Assuming you’re using Plasma 6, do the following.

1. Make sure KWallet PAM is installed

On Ubuntu/Kubuntu/Debian:

sudo apt install libpam-kwallet5

On Arch:

sudo pacman -S kwallet-pam

On Fedora:

sudo dnf install kf5-kwallet-pam

2. Check your wallet

Open:

kwalletmanager

Your main wallet should be named:

kdewallet

Most importantly, its password must be the same as your Linux login password. PAM needs this because it uses the password entered into GDM to unlock the wallet. (Arch Linux Wiki)

If necessary, in KWallet Manager use Change Password and set it to your current Linux password.

3. Configure GDM PAM

With GDM, the relevant PAM configuration is normally:

/etc/pam.d/gdm-password

First check whether KWallet is already configured:

grep -n kwallet /etc/pam.d/gdm-password

For Plasma 6, you want KWallet PAM involved in both authentication and session startup. For example:

auth     optional    pam_kwallet5.so
session  optional    pam_kwallet5.so auto_start kwalletd=/usr/bin/ksecretd

The ksecretd part is important on current Plasma 6 systems; older Plasma versions used kwalletd5. (Arch Linux Wiki)

Don’t blindly replace your gdm-password file. The exact placement of these lines depends on your distribution’s existing PAM stack.

4. Reboot and test

After rebooting, log in through GDM using your password.

Then run:

qdbus6 org.kde.kwalletd6

or check the processes:

ps aux | grep -E 'kwallet|ksecret'

You can also open KWallet Manager. kdewallet should already be open without asking for its password.

One important limitation

If by “login automatic” you mean GDM autologin, where you don’t type a password at all, that’s a different situation.

KWallet PAM normally needs the login password to decrypt the wallet. If GDM automatically logs you in without providing that password, PAM has no password available with which to unlock kdewallet. The same problem occurs with fingerprint-only login. (Arch Linux Wiki)

Source: ChatGPT – Ask: How to get KDE wallet service to login automatic when using GDM?