Have you looked through this list of instances?
Peertube
A free software to take back control of your videos
Peertube is an open, federated alternative to Youtube without advertising or tracking. On this site, you can find a good Peertube instance, with good rules, good moderation and most importantly a friendly community.
Dumb question, how do I know if I can upload videos without registering each instance and what size limit do they allow?
Do you mean 'without browsing each instance'? The list I linked to previously wont be much help there.
Your best bet might be to use the 'Find a PeerTube platform' search. The link I included here is filtered for video-makers who are not interested in live streams and are looking for a minimum of 5GB of space. You can adjust the filters to your preferences and/or needs.