Having played Halo CE for PC recently...no, it doesn't have split screen at all. That was only on the Xbox version (which is technically superior in quite a few ways). The only way to have split screen on Halo CE on PC is via console commands/mods. That said, I do agree with your overall point and I would love to be able to do split screen MCC on my PC without mods.
PleasantAura
It's the cost of federation with instances that try to be giant general-purpose instances (.world and .ee, mostly): just constant shitty takes that overwhelm participants in the conversation. Federation works far better with lots of small purpose-driven instances instead of gigantic ones; my small (<1000 users) specific community-focused Mastodon instance sees absolutely nothing like this and is full of people who intentionally engage in good-faith conversation with the rest of the community while every large instance I've seen has the same issues as centralized social media in that regard.
Is there another alternative? Bandcamp is the only similar website that a lot of artists I enjoy use.
Almost none of these groups actually care about the kids. Most of them actively support policies that are proven to enable/cause more abuse because it feels like they're hurting the bad guys. As a childhood survivor of a bunch of awful shit that I don't want to get into specifics on, I've never seen a single "for the children" group advocate anything that wouldn't have caused more trauma for me when I was younger. There's no care about fixing problems and preventing childhood trauma/abuse, just care about asserting control and investing in what "feels good": retributive justice (that's more likely to cause recidivism) against one single specific style of abuser while ignoring others (and the survivors) entirely.
This is more about feeling good (and, for some, more authoritarian control) than about actually helping the issue of child abuse.
It's pretty similar to most other roleplay in an RPG in my experience: you remember that you're all playing characters and you respect out-of-character boundaries (including fade to black for anything too explicit or indulgent). I've been worried about crossing boundaries before but I don't think I've ever actually crossed a line over the course of quite a few campaigns, even with the couple of times I've had to fade to black. You just have to know your players and be explicit about boundaries; I've had players request that no romance be present in a game before and I've accommodated that as well as players who've explicitly stated that they want to play flirtatious characters (though not in the same game, obviously).
And of course just be cognizant of how much detail you're going into; you don't want to be describing the details of a makeout scene, but "Jessica presses in for a long kiss" does the job and doesn't violate most people's boundaries in my experiences as long as they're okay with the general themes.
Never really had it go "weird", and honestly, though I've ended up in an IRL relationship with a player in one of my games on two separate occasions, the in-game romance doesn't seem to be related (neither of the people I ended up dating stood out in that regard).
If you're watching movies with friends and want a FOSS alternative, Jellyfin is the way to go. It's basically a way to host a media streaming center that others can connect to. It might be a bit overkill depending on your needs, but it's great for that exact purpose. It doesn't have chat or anything, though, so you'll want to keep something else around for that.
It's exactly why I don't participate in most communities for autistic people and instead look for those that brand themselves as neurodivergent-focused. There's a lot of "I had it bad so everyone else should have it bad too" as well as conditioned acceptance of societal issues in communities that label themselves as autism communities in my experience.