If you use 2 desktops in KDE, you can use different default browsers in these desktops. I like having Firefox as default browser for Personal desktop and Google Chrome for Work.

Create a shell script with logic for choosing

Let's put it into $HOME/scripts/smart-browser.sh:

#!/usr/bin/env bash
 
LOGFILE=/home/diz/temp/smartbrowser.log
current_desktop=$(qdbus org.kde.KWin /KWin currentDesktop)
 
printf '%s ' "$(date +'%Y-%m-%d %H:%M:%S')" >> "$LOGFILE"
echo "Current desktop is $current_desktop, Args: $@" >> "$LOGFILE"
 
if [[ "$current_desktop" == "1" ]]; then
    google-chrome "$@" >> "$LOGFILE" 2>&1
elif [[ "$current_desktop" == "2" ]]; then
    firefox "$@" >> "$LOGFILE" 2>&1
else
    firefox "$@" >> "$LOGFILE" 2>&1
fi