DM-ing with a stutter?

I have a friend who plays in my regular D&D game and has a pretty significant stutter. The rest of the party are great about this and are very patient and understanding, so I'm not looking for advice in that area, but this friend has also expressed a desire to create and run a campaign. I would love to play in his game, but I know he worries that his stutter would severely restrict his ability to be an effective DM. Unfortunately, at least as far as traditional DM-ing is concerned, I think he's just objectively correct. But that got me wondering - are there ways to work around his impediment or rearrange the typical flow of a D&D session that could allow him to do it?

Things we've considered:

• Asynchronous play by text (in Discord): This technically would work just fine, but it obviously doesn't feel the same as real-time play where everyone is in the moment together. IIRC, the last time we talked about this, he didn't really sound interested in pursuing it.
• Him doing the writing and prep and me actually running the game: This also would technically work, and I told him I'd be honored to do it, but I'm sure he'd prefer to not have to filter his ideas through someone else and trust that person to execute them faithfully. I know I would feel bad every time I failed to deliver something the way he intended. I also wouldn't be able to be a player for him if we did this.

Things I've wondered about but not suggested yet:

• Is there some sort of text-to-speech (TTS) engine that he could use to help him run the game in near real time? I'm thinking like a Stephen Hawking situation. This would relieve the social pressure of having to overcome the stutter, and it would also allow him to write chunks of speech ahead of time and just paste them in at game time. There would of course be delays as he types out improvised parts, but it would still be closer to a traditional experience than something like asynchronous play.
• Is there a way we could pull off a kind of co-DM arrangement where he's more involved in the moment, rather than simply writing and planning? This would still take me out of his pool of potential players, but it would be better than me just running the game by myself. What could this look like?

Are there possibilities I'm not considering? What tools and strategies could he/we use to mitigate this and help him be successful as a DM? Is there a way to dramatically reimagine what a D&D session looks like that might still be fulfilling for him and everyone involved?

Obviously the solution will be highly specific to him personally, and I'm not trying to solve all his problems for him without taking into consideration what he wants. We've talked several times over the years about his stutter and his attempts to eliminate it, and it's a conversation we return to every so often. I'd just like to have some ideas to suggest next time this comes up.

Thanks in advance, everyone!