There are plenty of tutorials around to make paper seed pots out of lots of good source materials, including sheets of newspaper and even your shredded paper bank statements. That last option is much more labor-intensive than the toilet paper roll option, since it involves creating paper pulp but hey, you might like that extra toil-for-soil experience
Alternatively, you can go the cardboard egg carton route, which is also a well-proven method. It might be a good idea with these and some others to poke some holes in the bottom to help the plant expand its root system once you transplant it.
Paper-Based Pots That Will Require Transplanting
You can use discarded paper drinking cups, but note that they’re lined with plastic so they’re only good until transplant time, at which point you can slice them open with an exacto knife and shake the small plants gently into your hand.
Another non-biodegradable option I’m considering: since my kids’ Lego advent calendar trays recently changed from plastic to paper, I’ve started reusing them as craft supply drawer organizers, but you could also section them off into seed starter pots (after all of the toys have been removed, they’re essentially a tray with small, rectangular compartments).