I am still using an external Western Digital Enclosure with a Thunderbolt 1 connection as an off-site storage device that uses HFS+. It requires an adapter to work with M-series Macs. When I bought it, 4 TB was a lot of storage, and I had no idea that Apple would abandon the Thunderbolt 1 port.
All my internal and external SSDs use APFS. I just don't see any advantage to converting the WD storage device to APFS.

WD 4TB My Passport Pro Portable External Hard Drive - Thunderbolt - WDBRNB0040DBK-NESN
WD WDBRNB0040DBK-NESN WD My Passport Pro WDBRNB0040DBK-NESN DAS Array - 2 x HDD Supported - 4 TB Installed HDD Capacity - 2 x Total Bays - Thunderbolt - 0, 1, JBOD RAID Levels Portable Overview: With the unique design of an integrated Thunderbolt cable providing both power and performance, My P...
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All my internal and external SSDs use APFS. I just don't see any advantage to converting the WD storage device to APFS.
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