Wa Alaikum Salam Wa Rahmatullahi Wa Barakatuh,
It is not permissible to eat the slaughter of any disbeliever, whether they
are dhimmi (a non-Muslim living under Muslim protection) or not.
Whoever it is permissible to marry, their slaughter is also permissible to
eat.
The disbelievers are Najis and their Najasa can transfer onto the food when it is being prepared which would render the Food Haram to consume and Najis as well even if it is plant based.
If one is certain that the food offered by the Non Muslims is slaughtered by a Muslim, it is not contaminated with Najasa then it would be okay to eat.
Similar is the plant based food offered by them.
And Allah knows best.
References : At-Tajreed fi al-Fiqh ‘ala al-Madhhab az-Zaydi by Al-Mu’ayyad Billah Ahmad ibn al-Husayn al Haruni
