Swaylock, but the one with effects. Using it to leave a blurred picture of the current screen without anything readable. Works well for two years now, is wayland only
None currently, because I live with my family and if I wanted to hide anything from them (which I don't), I could just switch to a tty, or log out. Most of my work is done in VSCodium or Vivaldi, which save their sessions, although I have considered doing one just in case.
I've always used i3lock. I also made a script to randomly select a background. Plus the login password circle thing looks cool. Would definitely recommend.
i3lock triggered manually with ctrl-alt-L from OpenBox. It's a force of habit to lock it manually, so no timer necessary. I3lock is lightweight, supports a background image, and has a nice fast password prompt with support for ctrl-u etc.
There was one I used to use that just made the screen black and had no visuals to indicate typing or anything working. Typing the correct password and hitting enter would unlock. I think there was some thing about it not being secure after some shift in typical Linux distro defaults and now I just use the default kde locker because lazy
Still haven't gotten around to setting one up but I plan to. Speaking of which, recommendations for Wayland screen lockers that can also act as a screensaver?
I thought that slock was too complicated so I wrote a tiny one for myself in Go using xgb. Less than 100 lines and pretty straightforward but it makes some assumption about my personal setup so not public.