@nina90 It's worth mentioning that you're not invested in "the US dollar" but rather invested in "US companies" (the dollar there is merely a unit of accounting, as you can buy a non-US domiciled S&P500 ETF like VUSA, denominated in, say, GBP).
It fluctuates based on what's happening in the global economy, but the S&P 500 portfolio of companies make about 30-40% of their income outside the US. Which is to say, you're getting pretty good non-US exposure.
Of course, you can consider adding a percentage of your portfolio to, say, an Emerging Markets ETF (to give you exposure to economies such as South Africa, Brazil, China; such as $VOO), and a rich world non-US ETF (exposure to companies in Europe; $VEA and $VHVE are examples).
Your options are limited or expensive, investing in these ETFs in a TFSA, and probably not the most cost effective way of doing so.
Also: The more targeted and niche your ETF gets, the higher the fees (usually expressed in TER -- total expense ratio) generally get. Note that ETFs that are denominated in ZAR are usually administered by SA companies, and charge a higher TER than those denominated in GBP or EUR, administered abroad.
There is virtually no difference between different S&P 500 ETFs. On your Easy Equities TFSA account, for instance, you can invest in the Sygnia Itrix S&P 500 ETF (0.19% TER) or the Satrix S&P 500 (0.25% TER -- 31% more expensive). If you, however, invested in the Vanguard S&P 500, in your Easy Equities USD account, the TER is 0.03% (making the Satrix one 733% more expensive than that one).
Consider using your annual allowance to invest in the lowest-cost broadest-market ETF (to me it seems the Sygnia Itrix S&P500 ETF is the one). Then use your annual allowance to invest in other low cost, broad-market ETFs that invest in companies outside the US (in addition to inside that market, as it is one of the most business friendly markets in the world, earning, as mentioned, a chunk of their money outside the US).