A lot of people consider walks in natural areas a substitute for church. It sounds like you're looking for something more organized though, with other people involved.

I think you are doing a great thing..I wish you the best with it.

I just left the area... I always recommend Dancing... it is an activity that can be used until your end of time. Teaches social skills no longer practiced. Music teaches discipline and there is no shortcuts or prayers... you do or you don't. Plenty of organizations. EX GF used to teach for Joy of Motion...bad management last couple years lowered their use but they are trying to return to the days when First Lady Michelle Obama used them to promote Culture.

how old are the grandchildren and do you get equal time with them if so just find fun secular activities so you become the fun grandparent just an idea