Hey, a true blue Singaporean here and learning 汉语 as well. My 母语 belongs to one of the race you mentioned. To be frank, its kinda hard to give you a straight yes or no answer if coming to SG is a good opp to 提高你的汉语水平.
Singapore by and large is a English speaking country. You can survive here without Mandarin, but cannot survive here without English.
For me, accent is one of my biggest observation. Singaporean Mandarin is pretty different from Mainland Chinese. If you can differentiate the accent, then well done, you are on a whole different level in your Chinese learning. Word usage too, but to be frank this should concern you like 5% towards your Mandarin language learning.
If you want to have a gauge how Singaporean Mandarin sounds like, please watch this movie in Netflix called “I not stupid” “I not stupid too”. The whole premise basically is set up from a Singaporean perspective. Disclaimer, movies were from 2002-2006. Even for myself, I feel that SG has changed so much over the years. Personally, I learn with Native Chinese teachers. Just a prefence for the 标准的普通话. To some Chinese SGreans, its 很难听. Overall, any native Mandarin speaker will have no trouble understanding one another despite the difference in accent.
In terms of Singaporeans attitude towards Mandarin as their mother tongue, some love it, some hate it. I guess you prefer to be in a company of those who loves Mandarin. I personally feel its not that difficult to find this group of people. Tons of videos on YouTube ridicule SGporeans not being fluent in Mandarin. I bet to differ. Most went through 10 years of compulsory Chinese learning, or slog their way through it. No offence to anyone, but to a 12-16 year old, having to memorise poems, learn about Chinese history, rote memorise 成语 is just so different to an adult learner whose learning it out of interest. I would say in terms of the information they learn, its definitely much more than the HSK materials. Okay I realise I digress quite a bit, but the point I want to mention is there are people here who are fluent in Mandarin. You will find them one, confirm guarantee plus chop.
Language usage
Most automatically talk to you in English. Reactions are different from Mainlanders too. Mainlanders usually will like “你的汉语怎么这么好?!” Singaporeans will most probably be like “你怎么可以讲华语”. Pretty subtle difference, one is in awe, with the other not so easily impressed but curious. But yes, if you speak in Mandarin to others, most will respond back in Mandarin. But opportunity to use Mandarin is not as crazy as China. You just have to make an extra effort to speak more Chinese.
If your preference is to follow a school curriculum, Advanced level courses are very hard to come by. Beginner to Intermediate are plentiful.
Standard of living here is pretty high. Cost is pretty expensive.
Chinese dialects is quite common among the elderlies.
I believe one of the biggest advantage is we have so many culture here, you wont just pick up Mandarin. You might even pick up Malay, Tamil and most importantly Singlish. And the ability to code switch.
