I thought HDR10 was genuine 10bit
Bit depth isn't what makes something hdr. You can have 10 bit sdr too. Wide color gamut is what makes hdr 'pop', and larger bit depth compensates the color precision loss due to the wider gamut. Higher peak brightness increases the contrast and technically the number of colors.
Acer seems to have made some naming fuckery with your monitor, as kg272 and kg272s3 have different specs. That must be why you found conflicting information. I found this listing of your model: https://www.amazon.de/-/en/Nitro-KG272S3-Monitor-FreeSync-Premium/dp/B0C28RM88F
And it says it does have hdr10 support but its srgb coverage is only 95%. With that srgb coverage I doubt it can actually produce the extra colors in a wider gamut, even if it accepts an hdr signal. I don't think you'll have a good hdr experience with this monitor.
I suggest you look into monitors that actually list their dci-p coverage and pick one with >85% coverage. Higher peak brightness is always better and will produce better images but I disagree with the sentiment that low brightness hdr isn't worth it. If higher brightness monitors aren't in your budget you'll still get a better than sdr image with a low brightness, wide gamut display.
Edit: same goes for deeper blacks via VA, oled panels or local dimming. They'll make more of a difference than brighter highlights and also be noticeable in sdr but still aren't as impactful as the punchier colors of a wider gamut. If you need to pick between specs, color coverage > blacks > highlights > bit depth.