My 9 year old Y5 is fine alone for an hour between her getting home from school and me getting back from work the day I’m in the office and she isn’t at an after school club. Many kids in the 8-12 range will be fine alone but some won’t. Some would be fine even a year or two younger for short spells and some even a year or two older won’t be. I think you really have to look at your child and not just their age.
Things to consider before you let them be home alone would be:
Are they happy to be alone? If they are worried about things going wrong or frightened to be alone then it’s not going to be a good idea.
Are they generally sensible and do you feel confident they are highly unlikely to do something crazy/dangerous left to themselves?
Do they understand and will they be likely to follow basic rules - no friends over, no answering door, no using hob/kettle, no going out or whatever else you feel is needed based on their current ability to manage problems that arise.
Are they aware of how to manage minor issues? As examples my two know things like how to clean up broken glass safely, what you have to do if you have a cut/burn, how to turn off the water supply, where the fuses are/how to reset them if a light bulb going flips them off (& where the torch is kept)
Do they know what to do if there was a fire or they were hurt?
Do they have a way to contact you if they need to check something?
Do you have friends/family very close by they know who they could ask for help if needed or they managed to lock themselves out/similar?
Have they already had short periods alone at home/resolved some problems like managing a breakage/spill with supervision and are they confident managing in those situations?