I was a teacher for ten years before taking a position at a small tech consultancy. I also encourage you to jump into the substitute pool; however, please understand that as a regular classroom teacher you will have many more tools to manage a high functioning classroom (not least, a regular classroom teacher has established relationships with their students). Substitute teaching is teaching, but there's a reason expectations for what's accomplished during that day are typically quite low. This all will change classroom to classroom, school to school - of course.

Definitely but it's good for anyone thinking about a career change to get a taste for the rougher aspects of teaching to ensure that they don't have unrealistic expectations about the career

Absolutely true.

I think there are many teachers who would love to have an experienced individual come in and guest-speak about one topic or another, if that's something of interest to people.

Definitely. It's much easier to engage with a class when you're not the main source of authority. It's like being the cool aunt/uncle.

Teaching is not easy and a lot of tech work is much less stressful than it

I have a number of family members who teach (or have taught) all ages and I feel it's one of the most important, difficult, and undervalued occupations out there.