What you see online may or may not be legit. There are multiple supply lines in the bike industry. It's been frustrating working at a shop when things are available to consumers (often parts intended for the OEM market moved into the gray market) but not available to consumers. I would personally rather use a well-known 3rd party brand (Kool Stop, for example) from a mainstream vendor than a possibly counterfeit pad from eBay or the like.

That pad shape is extremely common. They're on most entry level Shimano calipers and also most entry level Tektro, amongst a bunch of other smaller brands. I usually have stocked B01S/B03S because they're frankly normally inexpensive so why not go with the official Shimano parts, but given their unavailability I've been ordering a number of different 3rd party brands available through mainstream bicycle industry distributors like Koolstop and Tektro etc. They generally work fine.

M05 is, subtly, a slightly different shape.