I carry a spare tube, self adhesive patches, small multi-tool, tire levers, and pump on all my bikes. Since I use a leather saddle, also carry a waterproof saddle cover. Chain tool? No, but have never needed one during a ride in over a half century of riding.

If I see a cyclist in trouble, I usually stop but they usually have everything they need.

Last year someone needed my help. Had a new bike, wheels were fitted with tires and inner tubes, but their rims were the tubeless ready type rims and they did not have the hand strength needed to force the tire bead off the shelf on the rim. They had the spare tube and tire levers, but that was not enough. I got their tire off, but they chose to call a family member to pick them up instead of trying to fix it.

A couple times in the past couple decades, someone needed help because they carried CO2 and used up their cartridge without filling their tire. Needed to use my pump to top off the tire.

Instead of an app, if you carry a phone, a pump (instead of one CO2 cylinder) and the right spares for your tire size, you should not need assistance from another cyclist. Unless it is a serious ride ending problem, that is where the phone comes in.

If this is on a bike tour, the list of what to bring is much longer for what to bring, but I think you are only talking about a ride near home.