The only boards or computers with non-obsolete ARM CPUs and that are cheaper than the boards or computers made with Intel Alder Lake N CPUs, like this N200 or like the cheaper N100 CPU, are made by various smaller Chinese companies (Raspberry Pi have always been using obsolete ARM CPUs).

There are good ARM CPUs, like in the NVIDIA Orin modules, or in some boards offered by MediaTek and Qualcomm, which are derived from their smartphone products, but all these are very expensive in comparison with the Intel products.

If you are not scared by much higher than Intel prices, you can look e.g. for products including these:

https://www.mediatek.com/iot/products/genio1200-devkits

https://www.nvidia.com/en-us/autonomous-machines/embedded-sy...

(at the NVIDIA site you must ignore any module or devkit that does not include the word "Orin" in the name, everything else is too old junk, even if it appears to be cheaper)

For cheaper than Intel, but with performance at the level of the previous Intel Atom CPUs (i.e. Tremont-based, like Jasper Lake and Elkhart Lake) there are many products using the Chinese Rockchip CPU RK3588, for which much more public information is provided than for any Intel or AMD CPU, so I would trust it much more for implementing a secure appliance like a firewall, but not all of those products are well designed and some are overpriced (i.e. anything more than $200 for a complete computer with RK3588 is grossly overpriced).