The Toronto Stock Exchange has many securities traded in both USD and CAD currency within Canada. You can buy these stocks in CAD dollars or USD dollars, depending on the currency of your account. Generally, the US version of the same stock on the TSX will have .U at the end of the symbol to indicate USD. However, it's important to be aware that when you buy these .U securities, the default symbol for your account portfolio is the CAD symbol. When you sell the shares, be sure to sell the correct symbol to match the currency of your account to avoid foreign exchange. Attached is a list of current dual currency listed securities in Canada.
For example, the Ninepoint Bitcoin ETF trades in Canadian dollars under the symbol BITC, and the US version would be BITC.U. So if you purchased BITC.U in your USD TFSA, the buy would be in USD, and the value will show the USD value in your account, but the symbol will default to BITC (CAD symbol). To execute a sale of the stock in USD, you should be sure that you are selling BITC.U.