How do you load a third-party module in debian-installer?

I'm trying to install Debian Bullseye on a new Lenovo laptop (T14s Gen1). The laptop has a Realtek 8852AE wifi chip, for which currently no driver has been added to the kernel. There is a Github repository where a suitable driver appears to be present, and I'm able to build both the firmware and the kernel modules on another Debian Bullseye machine. I have created a Debian Bullseye usb stick and added my regular preseed file, which is working fine. I tried adding a series of 'early_command's, but d-i always throws an error at the first early_command it encounters. Any pointers what is wrong with it? ### Copy the Realtek 8852AE firmware during installation d-i preseed/early_command string \ /bin/cp /cdrom/realtek8852/rtw8852a_fw.bin /lib/firmware/rtw8852a_fw.bin; ### Modprobe the Realtek 8852AE network driver during installation d-i preseed/early_command string \ /bin/cp /cdrom/realtek8852/rtw89core.ko /lib/modules/5.10.0-8-amd64/rtw89core.ko; \ /bin/cp /cdrom/realtek8852/rtw89pci.ko /lib/modules/5.10.0-8-amd64/rtw89pci.ko; \ /sbin/depmod -a \ /sbin/modprobe rtw89pci; ### Copy the Realtek 8852AE firmware on target machine d-i preseed/late_command string \ /bin/cp /cdrom/realtek8852/rtw8852a_fw.bin /target/lib/firmware/rtw8852a_fw.bin; ### Modprobe the Realtek 8852AE network driver on target machine d-i preseed/late_command string \ /bin/cp /cdrom/realtek8852/rtw89core.ko /target/lib/modules/5.10.0-8-amd64/rtw89core.ko; \ /bin/cp /cdrom/realtek8852/rtw89pci.ko /target/lib/modules/5.10.0-8-amd64/rtw89pci.ko; \ /bin/touch /target/etc/modules-load.d/rtw89.conf; \ /bin/echo "rtw89pci" >> /target/etc/modules-load.d/rtw89.conf;