Unable to install onlykey-agent in Tails 5.10

Hello there,
looking for some advice re onlykey-agent and Tails 5.10
Installed prerequiste packages from guide

sudo apt install python3-pip python3-tk libusb-1.0-0-dev libudev-dev

and then pip3 install onlykey-agent
gave following output:

WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7c92fa2318b0>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/onlykey-agent/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7c92fa2316a0>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/onlykey-agent/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7c92fa2314f0>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/onlykey-agent/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7c92fa231b50>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/onlykey-agent/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7c92fa231d00>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/onlykey-agent/
ERROR: Could not find a version that satisfies the requirement onlykey-agent
ERROR: No matching distribution found for onlykey-agent