Roku has NTFS which is been superior to HFS and HFS+ for years. It is only recently that Apple has modernized with APFS which still lacks some features of NTFS though they are rather esoteric and it would be difficult for Apple to take advantage of them. APFS has features lacking in NTFS, each has its pros and cons.
The big disadvantage of using exFAT for sharing files with a ROKU is that MacOS (with UNIX as its core) cannot recover space on any kind of FAT drive without a full reformat. So if you are copying photos to the drive to display on a TV with a ROKU and want to replace some of the photos, with deleting and copying, you will run out of space on the external drive. Yup, after 55 years, UNIX still can’t do something as simple as erase a file and recover the space.
Net, the solution for now is to use HFS+ which is perfectly adequate for anything one would access on a ROKU.
