If I want to travel to another country and want to have foreign currency beforehand, where can I sell my BTC? I'm talking about selling BTC to a foreign currency before leaving my home country. Is this possible? And of course, is it legal? Just curious to know.
Any suggestions and/or recommendations would be greatly appreciated. Thank you.

If Bitcoin is illegal in the country you want to visit, your best option will be to sell your Bitcoin in your country. You can now change the local currency you have received from the sale to the currency of the country you want to visit. You can also change the money to US dollars because it is a globally accepted currency. Even if Bitcoin is acceptable in the country you are visiting, you may have to go through some bureaucratic process to be able to exchange your Bitcoin. So it will be better to exchange your Bitcoin before moving to the country. Although it is not secured, you might also consider a physical P2P exchange with a trusted Bitcoiner in the country you are moving to.