Personally I don't have much interest in murderhobo style evil playthroughs or roleplaying a main character who is just nasty. For my own evil playthroughs I tend to go for characters who are ruthless and uncaring. They have their own priorities and desires, and will sacrifice others in order to achieve them, but wouldn't go out of their way to harm others unless it serves their aims and might even help them if it's not too onerous and might get them a reward or some advantage down the line. They would also have no compunction about betraying, lying to, stealing from or even killing others in order to get what they want, so they'd also be far more likely than my good or neutral characters to choose that as an option for solving problems rather than, eg, persuasion or trading.
I also tend to dislike the idea of specific "evil paths" and prefer to be able to take twistier paths through the game, with lots of smaller decisions or opportunities to roleplay my characters' alignment. And I like playing deceptive, charlatan figures so I want to be able to join the baddies then betray them or use them for my own ends, or do the same to the goodies, and see the consequences on the game world build over time, rather than getting locked into branching paths.
So what I'm hoping for from Larian on the evil front, I guess, is a kind of subtlety. I want Larian to let me get into the good graces of Minthara and the cult while always intending to turn on them, then bring them down from within. I want to join with Halsin and the Harpers because I think it's my best chance of getting what I want but yet get plenty of opportunity to demonstrate my PC is no hero. I want to be able to betray the grove, but then let at least some of the tieflings escape. I want to be able to lie and cheat and betray and even murder (just not everyone!), and be given good and interesting motivations for doing so. I want to be able to satisfyingly roleplay evil characters with different motivations: selfishness, greed for money or power, hedonism, religious zealotry in service of an evil god, hatred of some or all people either just because or as a result of past trauma, prizing knowledge above any ethical considerations, and so on.
Which doesn't mean I actively don't want Larian to support murderhobos or nasty pieces of work who enjoy causing pain too - the more options folks have for playing the game the better - just that I can't imagine wanting to do any of the things suggested by the OP myself!
