Inquiry: Hookup of additional devices

I''m currently thinking through a personal need as well trying to be a bit more forward thinking.

Originally, I was going to make the suggestion of exposing UART via a 4 pin connector.

Then I realized that the pins for SPI0, I2C, _and_ UART are all unpopulated. Is there an opinion on whether the strategy is to stack boards, use a pass through header, or potentially expose any of these pins via a header in the future?