To confirm, if I schedule a meeting and invite all the scouts and leaders. The scouts and leaders with personal emails will receive a reminder and parents, of scouts without a personal email, will receive a reminder.
That parents of scouts who have been connected to their account will also receive a reminder, even if they are not personally invited, due to the way that Scoutbook enforces no one-on-one contact for email.
This also assumes none of the various adults/youth have opted out of receiving Scoutbook emails. I’m not quite sure what happens if a parent opts-out, but their scout has not opted-out. I recall a discussion about that boundary case on the groups at one point, just not what the outcome was.
The extra step you did not list is setting a reminder to go out to the invitees.