Wherever you are you will likely find a number of brands. APC is one that seems to be known internationally, and has a good reputation, albeit a bit pricey.
I suggest you discuss your needs with a sales assistant at a reputable store. You should get a UPS with enough capacity to last 15 to 20 minutes.
Most, if not all will protect against power surge, but make sure it has a three pin plug, and your household circuit is earthed.
For a UPS that protects against power fluctuations look for one that has AVR (Automatic Voltage Regulation).
I got my first Mac Mini in 2005, when I was living in Thailand. The neighbourhood had a very poor mains power supply, and outages were frequent. I was at the end of the line and some evenings there was not enough grunt to kick the fluorescent lights into action. I got a fairly basic UPS, which gave me back-up and supposedly surge protection, but without AVR the power supply brick that came with the Mac Mini was working hard. Not helped by having only 2 pin plugs in the apartment.... if I touched the computer I felt a little tingle.
That UPS failed nearly just over a year later, out of warranty but repaired at no cost to me.
In 2008 there was a massive power surge that cut the electric power supply to most of southern Thailand for several hours. It destroyed that UPS, but the computer survived.
I went looking for an APC, but none were available, so I got another brand. Cannot remember what it was, but they reckoned was OK, ensuring I got a 600VA model with AVR. It was a little more expensive than some others, but it had the features I knew I wanted. With the permission of my landlord I drove in a 2 meter copper stake beside the building I lived in, and earthed a couple of the sockets so I could use three pin plugs. No more tingling if I touched the Mini.
Soon after that the electricity supply to the neighbourhood was upgraded, so we could rely on getting a decent voltage.
However, after 4 years of hard work, the Mac Mini power supply was getting a bit dicky. When the HDD failed in early 2009, replacing it and the power supply would have set me back more than half the cost of a 2009 Mac Mini. Replace rather than repair the 2005 original was the sensible decision.
With the upgraded and earthed mains supply, the new UPS worked fine. Had the battery replaced and a general check over every three years or so.... it was still good when I left Thailand late 2019.
The 2009 Mac Mini was still in use here in my home country until recently, with the power supply still working fine. Still with the original HDD, it was getting a little noisy, so I reckoned it was time to replace it with an M1 Mac Mini about five months ago.
Where I live now the mains supply is reliable, with a steady voltage and power outages are rare. Not many folks bother with a UPS, but I still think it is prudent to have one.
Not sure what brand I got, but it says SAFEGUARD and DYNAMIX on the case. It is 600VA capacity (so probably good for 20 - 30 minutes with my set-up), and has AVR. There are 3 back-up sockets and 3 more surge protected sockets. It has a USB connection to the computer, which monitors the condition of the battery.