I was fortunate to have a wonderful father. It wasn't until it was almost too late that I realized and thanked him.
Be firm, but reasonable. Be kind and sensitive. Tease because it gently builds tolerances. Lift up and build up, don't break down.
Encourage communication and support with understanding. Don't punish honesty. Encourage it and meet it with respect. Even when honesty reveals a wrongdoing, communicate the next steps to right the wrong. Help them walk those steps. But sometimes, let them take some of the steps alone to build independence.
Be there to catch them when they fall. Be there.
Solid clarification and expansion there.
For the sake of expanding on cultural/social differences in other places, here in South Korea, most folks i see on dating apps in their 30s are without kids.
It's in the 30s that most relationships turn serious and get married.
I know two people here who got married in their 20s and had kids. Even the one who got married in their early 20s is open about how she maybe rushed into it.
My time in Canada supports everything you've said, mind you. If I hadn't experienced life here in Korea for so many years, I'd probably wholeheartedly agree without realizing that without knowing where OP lives, it's hard to describe what their potential dating windows are.