Was browsing Amazon and found this RGB RAM
https://www.amazon.com.au/Patriot-Viper-Gaming-DDR4-3600MHz/…
4133 and 4000mhz variants are 199 and 189 respectively, and the non-RGB versions are apparently Samsung B-Die (reference: https://www.guru3d.com/articles_pages/patriot_viper_steel_40…)
Checked on B-die Finder but only 4133mhz version listed on there, managed to buy the last one. 4000mhz Steel (non-RGB) is also listed, and I would assume the RGB would be using same chips as Steel but haven't looked more into this.
Still 2x 4000mhz left for anyone interested, even if non-b-die seems like a pretty good deal for freq and timings