Buy a Clary if you can find one. Those are normally sold for support of IT, medical and military applications. They’re not sold as consumer items.
The rack mounts show up frequently on eBay. Heathkit/Zenith UPS units from back in the day are Clarys too.
If you get hit by lightning the charge circuit, and the unit, will be toast. I’m not sure if the sine wave gen circuit survives or not. Anything connected will survive.
When I was working for Bell in S Fl doing business repair peeps would gripe after a storm that their UPS got taken out.
I would tell them you bought it to protect your Comp System and it did, whats the prob.