If the number of bad sectors is a multiple of 8, the software is probably counting logical sectors of 512 bytes each, while the disk has physical sectors of 4096 bytes each. Each time a physical sector fails, the software counts it eight times.
Still worth replacing the disk – a functional disk shouldn’t have any bad sectors.
QNAP NAS at work syncs to externally mounted disk once a day (one way mirror)
You can get cheap versioning here: instead of syncing to one external disk, get another disk or three and swap between them on a regular basis. As long as you realize that ransomware has encrypted your data before you’ve cycled through the entire set, you’ll still have an old backup you can recover from.
I’m sure you can find some Chinese company selling them, but there’s no point: the Gutmann method is designed for hardware that hasn’t been made in the past 30 years. With modern hardware, a simple zero-wipe will stop anyone short of a three-letter agency, and even waving a degaussing wand over it will stop most attackers.