A friend did that once and worked surprisingly well, I will add that to my list of options.Didn't see this post before.
Your friend is SOL. 5e is very simple already. I really like it but if we're being honest it has only just enough depth not to be braindead, so anything easier than it is likely to feel a bit flat. Maybe look into houseruling some RPG rules onto a wargaming system instead. Many of those are meant to be played with very large numbers of models so speed is of the essence there, and since they're combat-focused you rarely get more than just the combat stat block on a unit/model (which speeds up encounter design).
I was also looking at ORE, it didn't seem all that complex.
Mearls got kind of cancelled a year or two ago, he had to stop posting on twitter and streaming after an employee got outed as a wife beater and/or abuser, it turns out mearls had defended the guy when a woman went to complain, then gave the guy a of the people who had complained, which he then went and harassed.Did the Orion Black situation result in anything of note? I had a few people link me the Tor article but nothing else. I guess cancel culture hasn't hit Wizards of the Coast yet?
More recently mearls was replaced as the lead of D&D 5e and put in a less public position, although I am not sure if that incident had anything to do with it. Either way, all of his psionics playtests were scrapped and instead we got a really awful set of psionics subclasses with the shittiest mechanic ever.
Edit: There is a hashtag called #firemikemearls
Edit 2: got some of the details wrong, mearls didn't defend the guy, he just wanted proof. And all this shit happened 6 years ago, got brought up 2 years ago and nowadays the average twitter user won't even be able to tell what mearls did.