Any pointers for a regular Joe Shmoe homeowner looking for a backup battery? The Tesla Power Wall stuff and similar costs are halfway to six figures.
What I've done and would suggest is right now looking for battery banks for big ticket important items that you'd want to stay on anyways in terms of an outage. A lot of those can function as a UPS. You can get a 1kWh battery pack for $400 right now. A comparable home battery backup is charging $1300 per kWh of installed storage.
I currently have a 2kWh battery pack for my computer/server/tv and a 500Wh pack for my fridge. Works great and it's pretty reasonably priced. The 500Wh gives my fridge an extra 6 hours of runtime after a power outage.
If I wanted to power shift, I have smart switches setup so I can toggle when I want to.
I hesitate to offer any brand advice, because that is very situational, depends on what you're after, what experience level you have, what trade-offs you want to make, etc.
The cheapest per kwh way I could find to buy a home battery (that didn't involve diy stuff) was to literally buy an EV car with an inverter... by a factor of at least two... I ended up not buying one.
Unfortunately cheap batteries doesn't translate to reputable companies packaging them in cheap high quality packages for consumers instantly.