Is it not FOSS?
Feel free to DM at any time. I started learning it to build nostr:npub1current7ntwqmh2twlrtl2llequeks0zfh36v69x4d3wmckg427safsh3w in January and loved it ever since. LFG
Discussion
It is: https://github.com/starbackr-com/current
There are some restrictions around using the wallet service though (premium service).