In 2023 I still have to use AHK to be able to show/hide bookmark bar by a keyboard shortcut in Opera.
For those of us who don't rely on devs to ever implement it, here is the AHK script in V2 syntax. Pressing ctrl b will toggle the bar.
#Hotif WinActive("ahk_exe opera.exe")
^b:: {
sleep 100
sendinput "{lalt}"
sendinput "b"
sendinput "s"
}