KeepassXC 2.7.6 was released last week with alleged support for unlocking using a nitrokey 3 as per Release Release 2.7.6 · keepassxreboot/keepassxc · GitHub
Support on the nk3 side was shipped in fw 1.5.0 Release v1.5.0 · Nitrokey/nitrokey-3-firmware · GitHub
However… keepassxc does not seem to detect my nk3a mini… 
karthanis@karth-dev-book ~ % nitropy nk3 status
Command line tool to interact with Nitrokey devices 0.4.39
UUID: <redacted>
Firmware version: v1.5.0
Init status: ok
Free blocks (int): 237
Free blocks (ext): 474
Variant: NRF52
KeePassXC - Version 2.7.6
Revision: dd21def
Qt 5.15.10
Debugging mode is disabled.
Operating system: Arch Linux
CPU architecture: x86_64
Kernel: linux 6.4.11-arch2-1
Enabled extensions:
- Auto-Type
- Browser Integration
- SSH Agent
- KeeShare
- YubiKey
- Secret Service Integration
Cryptographic libraries:
- Botan 3.1.1
HMAC Challenge-Response was configured on nk3a mini:
karthanis@karth-dev-book ~ % nitropy nk3 secrets list
Command line tool to interact with Nitrokey devices 0.4.39
01. HmacSlot1 Hmac/Sha1
I did some troubleshooting using this thread: How to use HMAC-SHA1 Challenge Response with NK3 · Issue #281 · Nitrokey/nitrokey-3-firmware · GitHub
- pcscd is running
karthanis@karth-dev-book ~ % systemctl status pcscd
● pcscd.service - PC/SC Smart Card Daemon
Loaded: loaded (/usr/lib/systemd/system/pcscd.service; indirect; preset: disabled)
Active: active (running) since Tue 2023-08-22 20:41:19 CEST; 6min ago
TriggeredBy: ● pcscd.socket
Docs: man:pcscd(8)
Main PID: 26143 (pcscd)
Tasks: 9 (limit: 9360)
Memory: 2.8M
CPU: 353ms
CGroup: /system.slice/pcscd.service
└─26143 /usr/bin/pcscd --foreground --auto-exit
août 22 20:41:19 karth-dev-book systemd[1]: Started PC/SC Smart Card Daemon.