What is the ruling on a group of individuals visiting people and inviting them to Allah, and traveling to different countries to invite people to Islam, and dedicating time for that? And is this act considered an innovation (bid‘ah)?

This work is a form of inviting to Allah, and its doer will be rewarded, for the Prophet, peace and blessings be upon him, said: "Whoever guides to a good deed will have a reward like that of its doer."

The blame of blamers should not deter you from it.

Cooperating with those known for sound عقيدة (creed), knowledge, and good conduct is permissible, for Allah Almighty said: "And cooperate in righteousness and piety."

And your going out with a group whose members lack religious knowledge is permissible; in fact, it is an opportunity to teach them, advise them, and forbid them from innovations and transgressions.