How to merge two local subnets?

Question

Computer networks

There are two Raspberry Pis. The first RPi has no networks connected. The second RPi is connected via an Ethernet cable to the Internet, or to a local network (192.168.10.x).
Every RPi has a wireless module. On the first RPi, a WiFi access point rises. The second RPi and some other devices are connected to this access point. For all connected devices, the dhcp server (which runs on the first RPi) issues ip addresses 172.24.1.x
How to make it so that any device that is connected to the first RPi via WiFi has access to the network that is connected to the second RPi via Ethernet. Those. any device must have access to the Internet or a local network.
Now the second RPi can ping all devices that are in the wifi network. But with the first RPi, I cannot reach devices that are on the local network that is on the wire.
Any guesses on what to do?

Answer 1

Reserve a static address for the second RPi on the DHCP of the first RPi, and write the issuance of routes to the subnet for the second RPi on the first RPi, specifying the address issued by the second RPi as the gateway. And allow packets to be routed to the second RPi, at the same time register a route to the Wi-Fi subnet of the first RPi on the DHCP server or hosts behind the second RPi. Further debug with sniffers, if it didn’t immediately take off.

Answer 2

Need to write routes