I have updated to Buster with this kernel version:
Linux raspberrypi 4.19.57-v7+ #1244 SMP Thu Jul 4 18:45:25 BST 2019 armv7l GNU/Linux
The dongle doesn’t appear in the list of network interfaces however, and dmesg shows:
[66106.822697] usb 1-1.4.1.4: new high-speed USB device number 10 using dwc_otg
[66106.969298] usb 1-1.4.1.4: New USB device found, idVendor=0e8d, idProduct=7610, bcdDevice= 1.00
[66106.969322] usb 1-1.4.1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[66106.969335] usb 1-1.4.1.4: Product: WiFi
[66106.969351] usb 1-1.4.1.4: Manufacturer: MediaTek
[66106.969365] usb 1-1.4.1.4: SerialNumber: 1.0
[66107.062612] usb 1-1.4.1.4: reset high-speed USB device number 10 using dwc_otg
[66107.199591] mt76x0 1-1.4.1.4:1.0: ASIC revision: 76100002 MAC revision: 76502000
[66107.207141] mt76x0 1-1.4.1.4:1.0: Direct firmware load for mediatek/mt7610u.bin failed with error -2
[66107.208149] mt76x0: probe of 1-1.4.1.4:1.0 failed with error -2
I assume this means the file mt7610u.bin should be somewhere it isn’t.