Still have one, still works. Would happily use it if it were still practical. I think you can still load OpenWRT on them, but there's no software route around the hardware being outdated and slow.
As a counter opinion to "too slow" in regards to 54Mbps, as it likely depends on your use cases. My WRT54GL was the primary family router until 2018 and even worked just fine for live video broadcasting. Even today it sees good use for video calls with no issues at all. Lovely little piece of hardware that refuses to die. Just a shame that OpenWRT has dropped support since 2013, which feels a bit ironic given their name.
Not a recent version, not from the last 10 years at least. They dropped even 8/32MB devices. On my Turris Omnia, the bare system with nothing else running takes about 70MB RAM, mostly because of kernel size. Linux itself isn't as light as it used to be.
The best you can do is put DD-WRT on it. AFAIK, they still use kernel v2.6 on devices this old.
