Well then. I honestly wouldn't recommend doing something like this with anything older than a Powermac G5, but you make do with what you have. And since you have Leopard installed, Leopard Webkit is a must in my opinion.
sourceforge.net
I say that because it generally runs circles around TFF, and the only reason no one makes it a main browser is because it's quite unstable. It hasn't been updated since 2018 or so, but it's still modern enough to do most things. Just generally be prepared for it to crash.
Browsing the web on a PowerPC Mac tends to mean using different web browsers for different things, since some are better than others and you're going to have to figure out which ones work on the sites you use. But for the most part, it's still doable, just slow.