Feel free to ask any Qs if any come up, there is ?likely? better value than the Wyze 5070 extended now a days, I looked and bozos still want like $100 for it. Getting AVX2 would be a solid W for software in the future and worth a minor increase in cost. An ARM board (as long as it has UEFI and can boot regular Debian - not a custom distro for the board) would be a solid move too, but you’ll not get Opnsense then - it’s openwrt only for ARM.
This of course is me thinking of pricing when it wasn’t AI bro “lemme order all your RAM on an IOU” stupid, good luck there!! Just opnsense does not need much RAM - like 3 GB is easily safe (mine is given 2GB right now; uses 600 MB right now but I’ve seen it go past 1.5 GB sometimes). Straight Debian will add a gig or so. So even 4 GB would be fine. Proxmox is needy so it’s not fine there, but cutting it out of the equation would make 4 work if you want to save. And you’d prob get away with a $5 16 GB optane M.2 drive from China (aliexpress) with just opnsense - it’s using 3.2 GB of the 16 I’ve given it. And the Optane drive will never wear out as a bonus.
Edit: I’d estimate stock Debian at ~6 GB used. I think both can fit in 16 GB, even with Debian loaded with Incus to run the Opnsense in a VM.