As a viable political statement, mass Facebook check-ins are...questionable, but harmless. They had a moment during the protests at Standing Rock in 2016, but it's unclear if it actually did anything to disrupt law enforcement. Snopes put out an excellent article at the time:
Here's Kim LaCapria from Snopes in 2016: "Underneath the claim was a genuine problem with the message, that people truly wishing to assist the protesters could do so simply by checking in rather than sending funds or supplies to support their efforts."
This problem is still relevant today. Why is AltNPS calling for Facebook check-ins, and not material support? Why ask for Facebook engagement and not mutual aid?