There is a large selection of routers or general purpose devices that can be used as routers (for example Rasberry Pi) on which you can easily run standard Linux distributions. You can configure such distribution to install software updates automatically and have a quite secure setup for years.
With these USB modems, although they run Linux & Android, the images are of course proprietary and you fully rely on Huawei for security patches. The patches also don't install automatically, you need to check for them, download and install by yourself.
Most IoT devices have the same problem, so I personally avoid buying them, although they can work behind your home firewall, which can protect against many remote attacks. GSM modem is your gateway to the internet, so you can't put a firewall at front of it.
With these USB modems, although they run Linux & Android, the images are of course proprietary and you fully rely on Huawei for security patches. The patches also don't install automatically, you need to check for them, download and install by yourself.
Most IoT devices have the same problem, so I personally avoid buying them, although they can work behind your home firewall, which can protect against many remote attacks. GSM modem is your gateway to the internet, so you can't put a firewall at front of it.