Option 1 would be the better way to go first imo. The 9400 was an ok CPU but those 9th gens are really starting to show their age. You’re also holding it back by only using a single stick of ram. Your RX580 can hold out a bit longer with a better CPU and faster memory in dual channel, but if you upgrade the GPU first you’ll still be seeing the same performance issues. If you do go with option 1, make sure you have the proper mounting kit for your heatsink. AM5 is very different from 1151.
Thankfully both boards support bios flashback so as long as OP prepares a USB drive ahead of time, they can update bios without a CPU.
Also agreed on the X*70s. Besides the OCing stuff you’ll see more pcie lanes but it doesn’t sound like that’s much of a concern for OP. Personally, with the small price difference and similar capabilities, I’d go with the one I thought looked better lol. The average user probably won’t notice any difference between the two.