You’d need a sample of startup files for your target OS. Mount EFI partition of your Mac and copy the corresponding folder in /EFI folder alongside with Apple.
You can mount using terminal or better use a clover utility to mount EFI partition.
If you run Ubuntu installation, it asks where you want to install the Bootloader. You can choose your Mac ...
I read your this article. Follow the steps outlined in the article with these adjustments. I'd set up three partitions instead of four: macOS, swap and Windows. I'd adjust the macOS partition to the size you want to for linux. I'd install linux over the top of the macOS partition.
I've set up a triple boot system before but I haven't tried this procedure. ...
Windows can't read APFS.
To get back to macOS you need to hold the Opt ⌥ key at startup.
BTW, don't ever let Windows adjust anything on your drive. Consider that Disk Management tool as a read-only utility. It doesn't understand how it's being fooled into thinking it's in charge & will break things.
When you have an encrypted disk with FileVault, the system needs to ask for an authorised user to login just after EFI boot. (no news here, just enforcing what most people know)
That logo shows your avatar because your user's avatar is inserted on the EFI boot image/nvram. At this point of the boot sequence, there is no Operating System loaded yet, it's ...
If the above don't work, which I imagine resetting the NVRAM won't since that's what you do each time, you can try the following:
Your Mac might be in Safe Sleep. To wake from Safe Sleep, connect
your Mac to its power adapter and press the power button. Make sure
that your Mac isn't turned off. If your MacBook Pro still won't wake
up, follow these steps to ...
Troubleshooting is often a process of elimination and does require patience, so you'll need to keep that in mind as you proceed.
The first thing I would do now is test your Mac in Safe Mode.
Boot into Safe Mode
Follow these steps to boot your Mac into Safe Mode:
Fully shut down your Mac
Restart your Mac
Immediately press the Shift key and keep it down