If you put away that Haiku might have issue with USB-C boot capabilities … then there’s another thing you must face with.
If there’s no legacy mode into the BIOS, then there’s a chance your UEFI BIOS does not support well, if you have no GPT partiton table on storage devices. I am not absolute sure in it.
In case optical media the installer media would be ISO 9660, so no problem. In that case the challange would be your UEFI firmware would support an external CD/DVD/BD drive to boot from.
The thing is, when you create an USB stick then it is changing, as there will be actual MBR partition map from the ISO image’s ISO 9660 TOC and its bootable part.
I mean on another computer you should create a Haiku installer with GPT partition.
I do not know surely if the official anyboot ISO is MS-DOS or GPT partitioned, but if MS-DOS …
There is a GPT partitioning type, when there is a CSM compatibility partitioning which was created to the opposite case then you have …
Hybrid MBR (LBA 0 + GPT)
In operating systems that support GPT-based boot through BIOS services rather than EFI, the first sector may also still be used to store the first stage of the bootloader code, but modified to recognize GPT partitions. The bootloader in the MBR must not assume a sector size of 512 bytes.[9]
… if Haiku installer image created this way, then GPT partitioning at boot does not issue,
as in your case the Installer works as GPT drive for Haiku, as Haiku use EFI to scan your disk, and your UEFI only BIOS surely detect and read GPT partition tables, and yet the older machine with BIOS without UEFI also can boot of it, as Haiku handle both of it.
Anyway, someone with better knowledge than me, can help you, and also the USB-C booting issue in the ticket above, and especially in your case, where only USB-C port present in the machine’s motherboard, would be resolved with a patch finally.
I would try an external optical drive with written Haiku boot CD/DVD, if you (or someone for you) can write CD or DVD (as nightly is still within CD size) - so if you can have such possibilities, and the machine can boot from it.
Good luck !
