My apu handles 300Mb/s with a dozen firewall rules without issues.

I haven't tested it on a 1Gb/s but @c17r said it works: https://news.ycombinator.com/item?id=25045963

I have an older alix one, and I think it worked with 100Mb/s, but struggled after that.

Now, I bought my apu in 2016 and I don't regret it, but I'm not sure I'd buy one in 2022.