> Also, is it a good idea to connect a machine that has an unprotected operating system to the internet?

If the operating system has no IP stack or networking of any kind then it's probably ok

>I doubt that people could be convinced to pay money for it.

Monetary profit isn't the goal. Even the GPL is too restrictive for Terry, so the entirety of TempleOS's source is public domain.

I figured monetary profit was implicit in them applying to Y Combinator.

I don't think people understand that non-profits too need profits, they just don't take all of it home.

Non-profits need revenue, not profit.

But if your operating costs are more than your revenue (thus, no profit), who is keeping that non-profit afloat?

A non-profit organization can solicit donations big and small, via grants, memberships, and other common mechanisms.

A non-profit organization can also sell things at a markup. There are alarmingly profitable for-profit tote bag businesses riding the back of non-profits everywhere.

Like someone else has said in this thread. YC accepts non profits.

Extremely low latency would help for RTOS devices. Machine control like CNC milling machines and lathes and engravers. Software defined radio and other DSP topics. Aside from the previously mentioned HFT suggestion.

As a profitable application, consider the worlds best gcode driver with extremely advanced lookahead and real time guarantees. Just pump gcode in a serial port and drive servos out a parallel port as fast and smoothly as possible. The problem with selling an app is you might have built an foundation for an interesting class of apps, but you'd need someone with domain specific experience to write the app.