Zap success on my end! This request-response was slow AF though...it took several seconds.
Discussion
Thanks man!
I think the bottleneck here is likely fetching the invoice. It's like the perfect storm of slow a Python flask server requesting an invoice from a tor node on a raspberry Pi.
Need to do some more investigating to see if there is anything I can do to speed this up a bit or experiment with clearnet.
I think I am European, Swedish in fact.
How is that working out for the hoppfull?
Mama says, "Truth is all that matters
Lying and deceiving is a sin"
Drifting through a world that's torn and tattered
Every thought I have don't mean a thing
Don't stop, don't stop the dance
No more music
Don't stop the dance
Mama says, "Love is all the matters
Beauty should be deeper than your skin"
Living for the moment, lips and lashes
Will I ever find my way again?
Don't stop, don't stop the dance 
Probably you can try to make wireguard private tunnel (or other tunnel method) between your flask server and raspi. It should be more stable instead of tor 😅
I have done that on nodes in the past. I have a semi working wireguard setup script that sets up both the client and the server. Might try to tweak that and the documentation a bit to make it work with this.
Oh nice, it will be easier for you if you have already some setup
Just in case you want to try and play around with different tunnel tools or methods, you can probably look at this