Google offers free fabbing for 130nm open-source chips

How "bad" is that compared to standard/common 14nm, etc...

That sounds pretty huge. I've never seen on Hackaday or similar people getting small runs of chip fabbed. What are the broader implications of this? Will other fabs start to lower the barrier to production as well?

This is amazing.

I think the main reason why open source has taken off is because access to a computer is available to many people, and as cost is negligible, it only required free time and enough dedication + skill to be successful. For hardware though, each compile/edit/run cycle costs money, software often has 5-digit per seat licenses, and thus the number of people with enough resources to pursue this as a hobby is quite small.

Reduce the entry cost to affordable levels, and you have increased the number of people dramatically. Which is btw also why I believe that "you can buy 32 core threadripper cpus today" isn't a good argument to ignore large compilation overhead in a code base. If possible, enable people to contribute from potatoes. Relatedly, if possible, don't require gigabit internet connections either, so downloading megabytes of precompiled artifacts that change daily isn't great either.

How much has the power efficiency improved between 130nm and 7nm? Is it plausible to get better performance/watt for a custom chip on 130nm vs a software application running on a 7m chip? I get that hardware has other benefits but just wondering for accelerators where the cost/benefit starts to make sense.

I wonder if you can make micro machines at this level? The MEMS thing.

I always wondered why you needed gearing mechanisms in a micro machine. Has there ever been a practical application for gears in MEMS?