What's the 2020/Catalina method of getting my Mac to boot with Windows Bootcamp next time only?

It seems that pre-2015, the world and his mother wanted to get Bootcamp to boot to Windows just once, and keep the default startup disk as Mac. There are loads of threads that say to use Bless or Bootchamp: https://superuser.com/questions/36266/boot-camp-is-it-possible-to-restart-directly-to-windows-from-mac-os-x/167577#167577, how to quickly reboot from OSX to Windows and back.

But, these methods no longer work, it would seem.

I found this Reddit post which says to use sudo systemsetup -setstartupdisk /Volumes/.BOOTCAMP/WINDOWS && reboot, but I don't think this sets it to boot next time only; and all the advice I've read says not to test out sudo commands without fully understanding them, which I certainly do not.

So could anyone tell me, or point me towards some information that would get this to work for Catalina. I'm either looking for a modern version of Bootchamp (though, I'm sure Googling it would have got me to it if something like that existed), or a new way to run sudo bless -mount "/Volumes/BOOTCAMP" -legacy -setBoot -nextonly;sudo shutdown -r now.

I know I'm lazy and holding down the option key when I need to boot to Windows really isn't all that problematic, but I think I may have a faulty option key, as sometimes it boots to mac a few times before finally working. It would be so much easier if it could be done with something like the command above.

One primary purpose of the "nextonly" option is to allow for installation of a startup manager. For example, if you install rEFInd as a boot manager, then you would configure the Mac to always boot to rEFInd. This boot manager can be configured to display different operating system to boot. After a selection is made, rEFInd instructs the firmware to boot this operating system once. After the selected operating shuts down or restarts, the firmware will boot back to rEFInd.

One possible solution to your problem would be to install rEFInd and configure to allows boot to macOS after a small delay. You could then during this delay choose to boot instead to Windows.

rEFInd has implemented a new feature that allows you press a number at startup. This number is stored in the keyboard buffer. When rEFInd starts up, the number is read from this buffer. If the number matches a menu item, then the operating system matching the item will boot. This feature was implemented to avoid having to make a select during the small delay mentioned in the previous paragraph.