If I have 100k available to invest, what could I consider if I like to have Singapore, China and US exposure in equal amount?

34% CSPX

33% MCHI

33% Lion-Philipp S-REIT ETF

To directly address your question, your cheapest options would be to DIY and get into STI ETF (Singapore), S&P500 (US), and your choice of something like iShares MSCI China ETF (China).

However to build on that, it may be worth considering if you'd potentially benefit from further diversification through other ETFs like IWDA (Developed Markets, with mostly US) and EIMI (Emerging Markets, with mostly China).

The case for US vs Developed Markets has been commonly debated, and it's up to you to make a call as to which you prefer. However, you could be much better off with EIMI vs China, as EIMI is a lot larger and liquid as a fund with lower fees. Emerging Markets are also a lot more volatile than Developed Markets, so you'd have to be careful and make a conscious decision before you decide to concentrate your bets on China.

Assuming you still wish to go ahead with China / Emerging Markets, it very much depends on which roboadvisor and the portfolio being offered. To my understanding, most robos will also lean toward diversification by buying a small amount of Emerging Markets, as opposed to a very concentrated bet on China alone. However, robos also tend to charge a hefty 'convenience' fee on top of the funds (all in up to ~1%), as opposed to DIY into large and liquid ETFs (~0.2%).

You'd also be looking to reduce your commission costs as much as possible, given you're just at the start of your investment journey. Your current brokerage and CDP account will only work for your Singapore holdings, but you'd need to set something up for the overseas markets.

Ultimately, Interactive Brokers has worked well for me as a preferred brokerage, since they have the lowest fees if you're looking to invest on a frequent basis (and without the sneaky custodian fees, which charge a % of your total holdings periodically). If you do, feel free to use my referral link for sign up bonuses once you start investing with them (https://ibkr.com/referral/junjienelson797). Alternatively, you can also check out others like TD, though you have to be careful with custodian charges which gradually snowball as your holdings get larger over time.