if u are not tech savvy, consider a model with local warranty, any issue, can go to service centre
there are no benefits of flashing a china rom phone with global rom, it is for some people who don't mind tinkering with their phones, and they get to have more choices, compared to the models sold officially locally
FYI, there is no need to flash rom, if you just want to install apps via google play. some china rom phone can work locally with google play store that is side-loaded, but sometimes there will be some limitations, and also in the past, issues of missed/delayed notifications
realme, not many models sold officially in singapore now, if u are considering, can consider travel to JB to buy, many realme models sold officially in malaysia, at least it will be global rom, and if there are any issues, still can got to service centre in malaysia
https://www.realme.com/my/
FYI, this is off-topic already, to discuss further, suggest u start another thread in the mobile sub-forum
last point, if u are not particular on a specific area/feature, for $300 budget, value-for-money choice is poco f4. this model EOL soon, u think some more, it will disappear from the poco shopee or poco lazada store soon