DEs dont use mount
and fstab, they use udisks2
which works with polkit, GUI prompts or rootless.
Using udisksctl
prevents a ton of breakages.
I dont know about how autostart files work anymore, I always thought just place stuff in ~/.config/autostart
but now those dont work anymore on KDE, sometimes.
I think you use your init system for that. If you go fully rootless, you can create a user systemd service that mounts the drive.
mkdir -p ~/flashdrive
cat <<EOF > ~/.config/systemd/user/flashdrive-mount.service
[Unit]
Description=Mount flash drive on /dev/sda
#After=multi-user.target
[Service]
Type=oneshot
ExecStart=/usr/bin/udisksctl mount --block-device /dev/sda --mount-point /home/$USER/flashdrive
RemainAfterExit=true
[Install]
WantedBy=multi-user.target
EOF
systemctl --user enable --now flashdrive-mount.service
Not sure if After=multi-user.target
and WantedBy=multi-user.target
twists the space time continuum or something.
I am always kinda confused by those targets, as you must state one.