This is brainstorming for what I might try if I were in your situation:

- try contracting! There are a lot of people who need a basic MVP written and do not have the skills themselves. Not everyone has a tight deadline, either, and if you're paid hourly, if you are too tired to work one day, no problem, they just don't pay you. Just set good expectations ("I can only commit to 20 hrs/wk, but may be able to do more", no need to mention why). Between skills, availability, and rate, there is a lot of room to maneuver: a very skilled US developer who can only work 10 hrs/wk but who charges a low rate might be quite worth it. (But choose clients carefully) I know Toptal has had a lot of these kind of jobs, and I expect the other agencies also have a lot.

- look for companies with lower expectations. From what I've heard (i.e. HN comments :), often small, non-tech companies might find even basic stuff really helpful. Also, big companies have a lot of time spent not-coding.

- you could specialize in understanding code to fix bugs. Fixing problems in million line code-bases involves a lot of reading and experiments, not banging out code. This pairs well with contracting, but this is also an asset to big companies.

- if your pain is physical (e.g. wrists), you might try voice input. My brother knows a blind developer (who uses Linux [!]), he presumably isn't typing 100 WPM, but is reliably employed.

- consider leveraging your technical abilities in other fields that don't involve typing/standing/sitting. As I understand it, technical sales (e.g. selling devices to engineers) requires understanding how the products benefit the customers and visiting customers, not cranking out code. "Applications engineering" is sort of like high-level tech support and consulting, and some engineering companies have a group like this.

- consulting to fellow founders. I'm sure you have something to offer.

- management or PM, and I assume you have experience with at least one of these as a founder. You can also do this as contract work; I've seen contract work for PMs, small team managers, and even CTO. (Presumably the CTO contract position was for a rather small company which was either too small to need a FT CTO, or bridging the gap until they found someone permanent.)

- tutoring HS math/science/programming. From what I've heard, tutoring rates can be quite good, especially if you target the market that can pay.

- if you need money right now, $1500/month at part time (80 hrs/month) is $19/hr, which is fairly achievable. This isn't fun or glamorous, but I know second-hand that doing phone support for AT&T, Verizon, etc. is paying about this; I expect they are always looking for people. My friend, who took the job (half-time) because of some physical limitations, went through a month of frustration, but came to an understanding of what the business goals/limitations are. He also quickly got promoted to trainer, so he enjoyed his role more. Not something you'd want to make a career out of, but it would stabilize the situation, and you'd still have 80 hrs to explore alternatives.

Also, this probably isn't a popular HN approach, but if your pain is physical, you could try divine healing. Find a charismatic church and ask for prayer for healing; if it doesn't work, at least it'll probably be a new experience. If you're near Redding, CA, the Bethel Healing Rooms has hundreds of people that come every Saturday, and I personally know a number of people that have been healed. (Don't read too much on the web, though, there are a lot of opposition to Charismatics that are opposed because of doctrine and take stuff all out of context. All the naysayers are really motivated to make websites going into depth about all the failings, but all the people that have a great experience don't have a burning desire to create websites about it, so search results are really skewed.)