The drives are based on Seagate's Mosaic 3+ platform, which "incorporates Seagate’s unique implementation of HAMR to deliver mass-capacity storage at unprecedented areal densities of 3TB per disk and beyond."
Seagate's press release is focused mostly on the large drives' suitability for AI-related data storage—"AI" is mentioned in the body text 21 times, and it's not a long release. But obviously, they'll be useful for any kind of storage where you need as many TB as possible to fit into as small a space as possible.
Although most consumer PCs have moved away from hard drives with spinning platters, they still provide the best storage-per-gigabyte for huge data centers where ultra-fast performance isn't necessary. Huge data center SSDs are also available but at much higher prices.
Seagate competitor Western Digital says that its first HAMR-based drives are due in 2027, though it has managed to reach 32TB using SMR technology. Toshiba is testing HAMR drives and has said it will sample some drives for testing in 2025, but it hasn't committed to a timeline for public availability.