Hassos firmware installation

Hello there, fellow HA user here. I’ve recently installed hassos on a RPI 3 B+, long story short, I need to support an USB dongle: the TP-LINK TL-WN722N. I tried plugging it in and it didn’t work.
After a few loops I noticed that the kernel module (ath9k_htc) responsible for this hardware is installed and loaded, but it can’t load the firmware needed for it to work. Such firmware is nowhere to be found on a hassos installation. The firmware should be located at /lib/firmware/ath9k_htc/htc_9271-1.4.0.fw . This file can be obtained directly from linux-firmware.

Now I tried installing it in a couple different ways to no avail. Buildroot does restrict the hassos installation quite a bit. So here’s my question: is there a way to add this firmware to a hassos installation without rebuilding hassos?

I tried copying this file in the hassos-overlay partition, but it didn’t work since this overlay uses bind mounts through systemd files, hence it is an “emulated” overlay.

For someone who might be interested:
In the end I couldn’t find an easy way to obtain the firmware in the build without rebuilding, fast-forward I switched back to hassbian for the second time.
I’ve been successful at rebuilding the buildroot image with the new firmware but I couldn’t get it to work properly with Network Manager for the purpose I needed (AP). I was successful at setting it up with hostapd but the amount of changes to create a functioning image would counter the initial purpose of hassos (systemd, dhcpcd, wpa_supplicant, dnsmasq etc.). Nevertheless I do think hassos should at least permit the administrator to enable/disable systemd units.

If, for any reason, you want to try the same approach here are the flags I used:

# Driver
BR2_PACKAGE_LINUX_FIRMWARE_ATHEROS_7010=y
BR2_PACKAGE_LINUX_FIRMWARE_ATHEROS_9271=y
BR2_PACKAGE_LIBNL=y

# WPA supplicant
BR2_PACKAGE_WPA_SUPPLICANT=y
BR2_PACKAGE_WPA_SUPPLICANT_NL80211=y
BR2_PACKAGE_WPA_SUPPLICANT_AP_SUPPORT=y

# Network Manager
BR2_PACKAGE_NETWORK_MANAGER_TUI=y
BR2_PACKAGE_DNSMASQ=y

# Networking utilities
BR2_PACKAGE_IW=y
BR2_PACKAGE_ETHTOOL=y
BR2_PACKAGE_ETHTOOL_PRETTY_PRINT=y
BR2_PACKAGE_WIRELESS_TOOLS=y
BR2_PACKAGE_WIRELESS_TOOLS_LIB=y

# Hostapd
BR2_PACKAGE_HOSTAPD=y
BR2_PACKAGE_HOSTAPD_DRIVER_HOSTAP=y
BR2_PACKAGE_HOSTAPD_DRIVER_NL80211=y
BR2_PACKAGE_HOSTAPD_HAS_WIFI_DRIVERS=y
BR2_PACKAGE_HOSTAPD_ACS=y
BR2_PACKAGE_HOSTAPD_VLAN=y
BR2_PACKAGE_HOSTAPD_VLAN_DYNAMIC=y
BR2_PACKAGE_HOSTAPD_VLAN_NETLINK=y