That small? I was imagining burying a shipping container under the driveway/front yard or something.

Most grid-scale batteries that large will have bigger inverters (usually it'll be inverters that can dump that energy in 2-6 hours so 500-150 KW for 1 MWh of battery) and require cooling systems and such, but if you're putting that in your home then cooling will be negligible and the inverter will remain small. The batteries themselves are fairly compact, it's the support systems that get large.

Shipping containers should never be buried. They are not designed to tolerate forces pushing in on the sides and can collapse.

What's the degradation cycle on batteries that size?

If you're using daily, do you get... three? five years?

Looks like - https://cartroubleshooters.com/how-long-does-a-tesla-home-ba... - ten to fifteen years with a guarantee of 10 years at 70% from Tesla

We can roughly estimate lithium ion batteries as 500 watt-hours per liter. Which makes a million watt-hours 2000 liters, which is two cubic meters. Add in extra overhead and it's still not all that much.