Most "device" BIOSes (for the stuff on the motherboard itself, like the IDE or SATA controller) are integrated in the motherboard BIOS firmware by the manufacturer of the motherboard.
Technically they are separate things, but you can't individually update/replace them.
Plug-in cards that need a bios (video-cards, SCSI controllers, some network cards (with "boot from network" capability) and FibreChannel host-adapters are the most common examples) have their own on the card itself. These days almost always integrated in the controller chip, but in the past (boot-roms on network and SCSI cards) they were sometimes separate EPROMS. In some cases you even could buy a card without the EPROM (in which case it wouldn't be a bootable device) and could buy the EPROM and upgrade later.
This was a thing when the first PCIe NVMe upgrade cards for PC's without SSD started to appear on the market a few years ago. There were a lot of cheap cards around that didn't have a BIOS. Those weren't bootable, so you could only use your brand-spanking new fast NVMe SSD as data-disk and not as system drive.
With more modern UEFI systems (UEFI is NOT the same as a BIOS even though many people call it a BIOS) it is also possible that the card doesn't have a bios/firmware chip, but instead the code is loaded from a file in the EFI partition, by the computers UEFI firmware.
(Rare though. Never seen that myself.)