Q.cross pollination of fruit trees
I am planning to plant a dwarf Meyer lemon tree and an Algerian dwarf clementine near each other. Is there a danger of cross pollination so that I would have neither lemons nor clementines? Thank you.

Dwarf Meyer Lemon is self-fruitfull, it will not cross pollinate.
Algerian Dwarf Clementine is also self-fruiting but will produce more seeds and fruit with cross pollination.
Here are some links to help you.
https://www.gardeningknowhow.com/edible/fruits/lemons/growing-meyer-lemons.htm
https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1001.pdf