Also, I wasn’t sure about the possibility of Wyll/Karlach staying in an evil playthrough as they both have very strong moral codes
They're both use morale when they feel comfortable with it. Sort of double standarts. Wyll has no problem with Mizora's pact or killing Karlach until you stongly push on him about it. Karlach justify thievery and obviosly not for grand purpose. They're just don't like you raiding grove with Minthara but they will accept any evil choice you will make in the future.
Same with Minthara tbh. She hates all gods for their cruelty and etc. But if you play as D. Urge she will inspire you submit to Bhaal and become his full puppet. Moreover she will persuade you if you tell her that you don't want to become chosen of Bhaal. Before that you could hear dialogue with her about Orin that she will murder and slaughter this world instead of rule over it and how this is bad. But when you will do the same - it completely satisfies her. Poor writing in act 3 as I see.
