Have been running between HK/CN/SG for a bit using the P50pro 888 CN version for a while with HK/CN apps, I have an iphone for SG so i cant say for an SG user. No problem here except some apps i cant use like HSBC Payme (HK ver of DBS Paylah), but Gbox has served me well for most of the GMS required apps (dont trust GBox for banking apps) like YUU HK, McD HK or even KMB bus app. CN apps i have absolutely no issues. Warm a little but HOS 3 is very aggressive in killing background apps so things are generally alright.
I use revanced for youtube and the only google app i need to run from gbox is gmaps. I use gmail IMAP to outlook app and my contacts are all on my outlook (including my iphone).