Welcome!
A wifi card was optional in the iBook until the last models, the Late 2004 and Mid 2005. I suspect the original cards will be hard to find, and third-party USB-based dongle solutions seldom had the required Mac drivers, and even those those that did were a royal pain for setup and maintaining a connection.
I would visit powerbookmedic.com to look for original cards.
Were this my iBook, I would use a wifi range extender. All iBooks have an ethernet port to which you attach the extender by cable. No drivers required, and most extenders have an ethernet port. It's not portable but would get you internet access.
A caveat based on my experience with our remaining PowerPC Macs: Few websites today will work with the ancient browsers associated with macOS 10.4.11. The one solution is no longer being updated but may work— TenFourFox. The last version released is available from the developer's site here:
https://www.floodgap.com/software/tenfourfox/
Do not trust any other download sites for this.
I've used 10-4-Fox on a G4 eMac running 10.5 and it is slow, can't do video, but works with older, less demanding websites. It gives you time to go put on the kettle!