Two Raspberry Pi using one USB LTE dongle

Question

is it possible to use two Raspberry Pi (4, 1 GB) with only one USB LTE dongle? How to configure it? USB dongle is connected to USB port of selected Raspberry Pi. The second one I'd connect using ethernet port.

EDIT: WiFi to share connection is more comfortable but I prefer easier solution (ethernet or WiFi). Current connection details (Raspberry Pi #2 is not connected now):

ip addr show
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0:  mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether dc:a6:32:05:32:c8 brd ff:ff:ff:ff:ff:ff
3: wlan0:  mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether dc:a6:32:05:32:c9 brd ff:ff:ff:ff:ff:ff
4: enx0c5b8f279a64:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 0c:5b:8f:27:9a:64 brd ff:ff:ff:ff:ff:ff
    inet 192.168.8.100/24 brd 192.168.8.255 scope global noprefixroute enx0c5b8f279a64
       valid_lft forever preferred_lft forever
    inet6 fe80::d661:d504:c3e5:d5a4/64 scope link 
       valid_lft forever preferred_lft forever

lsusb
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 12d1:14dc Huawei Technologies Co., Ltd. E33372 LTE/UMTS/GSM HiLink Modem/Networkcard
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Answer 1

If you only want to connect these two RasPis, then the simplest solution is to use the wired ethernet connection with just two static ip addresses. I assume interface enx0c5b8f279a64 on RasPi1 is that one from the USB LTE dongle. Now give its eth0 interface a static ip address, maybe 192.168.1.1/24. It must be different from the subnet 192.168.8.0/24 the USB dongle is in. Enable ip forwarding in /etc/sysctl.conf by uncommenting the line and reboot:

net.ipv4.ip_forward=1

On RasPi2 give its eth0 interface an ip address from the same subnet of eth0 on RasPi1, e.g. 192.168.1.2/24. Then you have to set a static route to the USB dongle on RasPi1 with:

rpi2 ~$ sudo ip route add default via 192.168.1.1 dev eth0

If using default dhcpcd networking then you can set this persistent in /etc/dhcpcd.conf with option static routers=. Just use the example given there and reboot:

# Example static IP configuration:
interface eth0
static ip_address=192.168.1.2/24
static routers=192.168.1.1
static domain_name_servers=1.1.1.1 8.8.8.8