In the world of smartphone repair, “USBUtil” or “USB Tool” is sometimes used generically to refer to flashing utilities. The most famous of these is the , which is specifically designed for devices running on MediaTek (MTK) chipsets. The number “300” could refer to a particular chipset or model (e.g., MediaTek MT6572 or Sintel V300 Star 9 ), but a standalone "USBUtil v300" is not a standard product name. The search query may also be aimed at finding MediaTek USB drivers, as these are a required component for SP Flash Tool to function properly.
opkg install usbutils
If you meant (part of usbshare package), it’s included in DSM and not available as a standalone download. For DSM 6.x/7.x, it’s in: usbutil v300 download install