I’ve noticed that more U.S. banks and agencies are flagging my VoIP number, and it’s making me nervous. Should I move my accounts to a physical U.S. SIM or use authenticator apps now to avoid a sudden lockout? I’d rather deal with the setup today than lose access to my money when I’m stuck abroad and desperate.

In the US, it's still not clear how Bitcoin is regulated. The CFTC calls it a commodity, and the IRS calls it taxable property. However, the IRS does not recognize it as currency. The lack of a single definition makes it harder for normal financial integration to happen because regulators aren't sure what to do.

Chase Sapphire Preferred, Capital One Venture X, and Amex Gold and Platinum would fulfill your requirements of no international transaction fees, airport lounge access, and many more.
Check all the terms and conditions properly (as each card have different perks and fees) and then choose accordingly.

There is no need to switch totally to ETFs. You can keep your stocks and add other ETFs like SPY or SCHD to your portfolio, as they provide more stability and broader exposure to you. My suggestion for you is to just maintain your core stocks and invest in ETFs for better diversification and for steady returns.

In the States, cryptocurrencies are considered taxed property. This means you must pay taxes on any profits you make from selling or trading bitcoin. There is no tax on just moving money from an exchange to your bank account; taxes apply to any earnings from trading or selling. You must maintain a record of your transactions for your tax returns, allowing you to track any gains or losses.