I was testing my backup/restore strategy to see if it worked and restored a couple of partitions with Acronis True Image. Unfortunately all my Linux boot entries were missing from the UEFI boot menu after restore. I could only boot into Win 11.
So a bit of googling and a full drive restore by Macrium Reflect and I was still in the same situation.
After a bit more googling (In Windows) I found efibootmgr which will run from a live USB of Solus. So if you find yourself in a position where all your boot entries for Linux are hidden, efibootmgr is the solution. You can unhide and edit the boot order so that you can get back into Linux.
The alternative to efibootmgr is EasyUEFI which can be run in Windows but I am not sure what the trial version does. It's a graphical way to change the UEFI menu.