Since several people have asked I'll post how anyone can do this, and it's not actually that complicated since I've already gotten the apk file and so can share that.
- If you don't already have a tablet you want to use you'll need to get one, I got the Amazon Fire HD 10
- On the Android device you want to use as your new Ergatta device download the Ergatta apk file from either my Google Drive or this short URL version of it: https://shorturl.at/IbRzJ
- You can use Chrome or whatever browser you have (Amazon Silk, etc). You might need to bypass some security restrictions on the device to download install this file. On my Fire's Silk Browser it prompted me that installing this app might be dangerous etc, but shows you how to bypass.
- Remove the old Ergatta tablet from your rower
- Attach the USB cable that was going into your old tablet into your new tablet, I'm using one of