I expect I'm not alone in getting an offer of 80% off the price of a Zwift Cog & Click via Rouvy last week, at £17.50 including shipping it's a good deal and much cheaper than buying a 105 cassette for my road bike for when I can't be bothered to move it over to the Kickr Core. I often leave my gravel bike on the trainer as I have a spare cassette for it, but as it's Sora (2x9) it can feel a bit of a slog sometimes with the larger jumps between cogs that 2x12 on the road bike.
Good bit of research on here led me to Bike Control, seems to work really well to connect the shifters to MyWhoosh and although it took a bit of getting used to completed the first stage of the Race to Pink Mission tonight.
The app is ~£5 after the trial period, but having saved £40 on the Cog & Click that seems very reasonable, especially as it can work with other platforms as well.