You didn't specify any preference for speed. If 2x16 DDR4-3600 CL16 sounds ok, try Crucial BL2K16G36C16U4B; that's a 2 kit of BL16G36C16U4B, which is on the QVL and no RGB. I'm seeing them still available from Amazon. Crucial are winding down their Ballistix line, exiting the gamer/enthusiast market, but their DDR4 is good and there's still some around. 3600 CL16 is a pretty good sweet spot for DDR4, a nice mix of performance vs price, but you're welcome to pay more for faster if that's what you desire.
Support can always point the finger at an unsupported RAM config if the symptoms could be related to RAM, so yeah, worth the extra effort to get a supported config if you can. I'm not saying they would do that unreasonably, just nice to avoid that possibility.
2 DIMMs is always easier to get stable. 4 DIMM DDR4-3600 is certainly possible, that's what I run on X570, but make sure the "socket support" column of the QVL is "1,2,4". If you were to go for some of the super-fast DDR4, 2 DIMM would certainly be more likely to work, and is required for stuff listed as "1,2" on the QVL for a supported config.