Select “Update firmware using precompiled image”, then select PureBoot. (PureBoot isn’t offered for automatic build from source because it is not 100% reproducible yet.)
Hello. I’ve been very busy recently and haven’t been able to try the methods you posted (but I will, of course). I just wanted to pop in real quick and say thank you for the reply and the help. Much appreciated. I’ll pop on again to say if it worked or not or if I hit any snafus.