I make it brief, the steps are pretty much universal for Firefox, Brave, Windows except that on Linux SNAP packages are not supported, but this is clearly mentioned in KeePassXC and also visible in the first screenshot.

• Install KeePassXC, on most distros pre-installed.
• Install the Chrome Extension.
• Install Brave as AUR package, the -bin release are good enough.
• 2FA works too, just click on the little bubble icon if you see the 2FA field.

On KeePassXC end we need to enable the integration

The advance options are optional and normally do not need to be touched. It is up to you if you change something here or not but the popups as return checks, that are enabled by default make sense and IMHO you should not suppress them to avoid accidentally overriding something.

On Browser and Extension side

Make sure you connect the database once you are finished, which will show a popup which you need to manually confirm, this is a simple security check.

In case you are on Brave Beta or Nightly and cannot connect your database to the KeePassXC Browser Integration.

• Copy the file org.keepassxc.keepassxc_browser.json to ~/.config/BraveSoftware/Brave-Browser-Nightly/NativeMessagingHosts replace nightly with beta, depending on what you use.