So after much consideration on whether I'd buy an OBDEleven, I ended up with a Carista dongle, after reading on Briskoda that its possible to use it to turn on the second set of bulbs fitted to the fog lights on my Mk2 Octavia.

Looks like it all works, I ended up buying the genuine Carista dongle as others I'd tried didn't behave themselves. Appears to be nowhere near the capability of the OBDEleven, but if you manage to find a dongle that works on it, its only ~$10 for a week's access to apply customisations.

Carista's yearly subscription isn't that cheap, but for many of us where a customisation is a one off, its quite cost effective if you can find an ELM327 that works with it, less so if you need to buy the genuine dongle.

It also allows adjustment of the rear brakes for cars that have electric park brakes too, although I didn't test that.

For $50 (including a month's access to the paid customisations and service tools), it does what I wanted. If you want more control over customisations, you're probably still better off looking elsewhere.