The biggest thing that PieFed has done is get up and running on public data with new accounts open to the public. This trial by fire will make it fail fast or become much improved. It seems that the main developer is quite experienced and has thought about architecture and improvements that have already been implemented. I think it’s promising for all of these reasons.
My biggest potential concern is that moderation tools have not been implimented yet (unless the were very recently).
As far as Python being difficult in larger systems, this can be mitigated by experience and good practice. But I tend to agree that Python is typically not the ideal choice for a large project.
They wrote ablog post about it
https://jewy.blog/2024/03/04/my-love-hate-relationship-with-lemmy