How to create a network bridge between wlan0 and et1 to a second eth0 device?

Question

I have a network topology as described in the linked image. Network Setup

I have a WiFi router on a private 10.12.12.1 network. An Ubuntu 20.04 box, on a Nvidia Jetson, is connected to the WiFi network with an IP address 10.12.12.z. The Nvidia Jetson has two physical eth0 and eth1 devices. I would like to connect a Debian Box that has a physical eth0 interface to the eth1 interface on the Nvidia Jetson.

I am not exactly clear on the networking terminology but I have started by bridging wlan0 and eth1 on the Ubuntu 20.04 using a netplan configuration as follows:

network:
  version: 2
  renderer: NetworkManager
  ethernets:
    eth1:
      dhcp4: no
      dhcp6: no
  wifis:
    wlan0:
      dhcp4: no
      access-points:
        "******":
         password: "******"
  bridges:
    br0:
      interfaces: [eth1, wlan0]
      dhcp4: true
      dhcp6: no

I am unclear what my next steps should be after this point?

I assigned a static IP to the Debian box along with subnet etc. At this point I cannot ping the Debian box. Am I supposed to assign an IP address to the physical interface on the ubuntu box? I did not think so because I thought the bridge basically makes the wlan0 and eth1 as a br0 device with the IP address being assigned to br0. Here are some outputs from bridge related commands.

CMD PROMPT>$ brctl show br0
bridge name     bridge id               STP enabled     interfaces
br0             8000.2046a10bbe78       yes             eth1


CMD PROMPT$> bridge link
    7: rndis0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 master l4tbr0 state disabled priority 32 cost 100
    8: usb0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 master l4tbr0 state disabled priority 32 cost 100
    12: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master br0 state forwarding priority 32 cost 100

I would appreciate a nudge in the right direction to make this a proper setup.