Haiku on Mac does depend on correctly initialised haiku partition signature, back in 2016 when I first tried to get it going I struggled due to incorrect Be file system signature created by paritioning tools, once I got that resolved (used a successor to gparted to write BeFS signature, I dont remember what it was called but you can browse the forum archieves), then I never had any issues with Haiku again on my MBP 11.3 (2014). This was over 8 years ago, you will have to dig through the forum posts I made back then to figure out exactly what I had to fix to get Haiku to just work when installing natively. Booting from external USB storage media always worked on MBP.
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