Sorry, I don't know how I missed that. I don't have any suggestions for a Opal as it runs the SiFlower SDK. I'd see if you could return it & get one of the following:
- Slate Plus (GL-A1300)
- Beryl AX (GL-MT3000)
- Slate AX (GL-AXT1800)
- Flint v1 (GL-AX1800)
- Flint v2 (GL-MT6000)
All of these support 'pure'/'vanilla' OWRT so if there's a package in the default GL repos missing it's a whopping three minute process to switch over to OWRT or back to GL firmware. In the case of the Slate AX you could just add them. See below.
The Slate Plus, Beryl AX & Flint v2 are the most promising ones for the lessen performance when giving up/getting rid of the proprietary SDK.