I don't know shit about this game. Can Phil skip every piece of side content and finish the game in 40 hours? Or would he really have to sink 80 hours into this game to beat it?
The game is pretty balanced around you doing at least some of the side content. If you skip it, you can end up pretty underleveled. There's only 12 levels, so even being one or two levels under the recommended can actually make a pretty big difference. With a broken build it doesn't really matter, and there's a lot of broken builds in BG3. But with a few exceptions, a lot of builds aren't things Phil can just look up and follow from a guide. They tend to rely on using specific abilities/setups/game mechanics, which your average (or even below average) gamer could easily figure out. So naturally, it'll be well above Phil's pay grade. As far as I know, there's really no OP facetank style build that Phil usually relies on. Basically, in order to be broken, you need to understand what you're doing, so Phil is screwed.
If he plays on easy it'll help, but I've seen people still get destroyed because they really don't understand what they're doing and just click on enemies. Once all is said and done, I think it's pretty easy to figure out the basics, but again, this is Phil we're talking about. He's already reluctant to engage with the game, and we've seen how he handles similar systems when he played Divinity.
I don't think this is going to be the greatest TIHYDP experience ever or anything like that, but I think we'll get a few laughs. The game is pretty popular and was heavily requested, and we've seen in the past, one of the few things that can get Phil's dents to turn on him is when he shits on their favorite game/characters. There's also a chance that because of said excitement, dents might be going all in with their tugboats, so Phil will have to keep going for at least a few sessions because of "positive support." I think the moment it drops even slightly, he'll pull the "alotta people" excuse to drop and bury it, then lean in anyone who keeps asking for it to come back.