https://github.com/bitcoin/bitcoin/
https://github.com/btcpayserver/btcpayserver
Anything else Bitcoin related
https://github.com/bitcoin/bitcoin/
https://github.com/btcpayserver/btcpayserver
Anything else Bitcoin related
What is this for? Is it a wallet for bitcoins that can run on ARM?
Bitcoin Core is a full node client / wallet.
BTCPayServer is a payment server to generate invoices for payments.