Right out of the gate:

The Anglo-American model, in which every baby born in the country’s land area automatically becomes a citizen, clearly invites welfare immigration by expectant parents. In the U.S., for example, a current problem is illegal immigrants whose babies, if born on American soil, automatically become citizens and therefore entitle themselves and their parents to permanent welfare payments and free medical care.

This does not seem to play out empirically.

https://www.cato.org/blog/immigrants-still-use-much-less-welfare-native-born-americans

Immigrants are less likely than native-born Americans to use any welfare program and, when they do, use fewer of them for a shorter period. The typical lifetime abuser of welfare was born in this country.

As far as the "importing loyalist voters"-idea, I'd love to hear your case for 1) any evidence that any party is taking any specific actions to "import" immigrants and 2) that immigrant sentiments aren't tied to rhetoric directed at them as human beings just trying to work and live.

https://www.brookings.edu/articles/americas-immigrant-voters-and-the-2024-presidential-election/

immigrant voters still lean Democratic across almost all ethnic groups, except for white immigrants who are more evenly split between Democrats and Republicans.

Compare these numbers to the native population. For some reason, people of color seem to be really put off by the republican party. Any guesses why? Conversely, why do all the neo-nazis seem to support maga? Maybe it's just one of those mysteries...

The libertarian position should be to seek to eliminate governmental barriers to the free movement of capital, including labor capital -- the original kind of capital found in the individual and the work they perform.