I will post it again since I guess you ignored it on the Github Issue.
We’re certain this is a burning question for all of you: Will there be a SixM? The answer is a little complicated for many reasons. However, assuming there will be a PC port, we cannot predict what the game is like, or how complex the systems are before we make any decisions. Only time will tell!
The Cfx.re Monthly Update - February 2022 edition discusses this, also reading all these monthly updates is very informational so I suggest doing so 
Simply, there is no way for anyone to know what it will be about, and it is impossible to even speculate. FiveM has grown a lot and has more people working on it than ever allowing for faster updates and more features, hopefully, this also allows faster development for ‘SixM’, if that is a thing. I suspect the reason RedM development is slow is that I believe there are only a few people, mainly @Disquse who are working on it, due to it being less popular I would assume they aren’t focusing much development time on it, RDR2 is a rather unpopular game compared to GTA V.