No, the BT400 only pairs to some limited brands of TVs only. And there is no IR learning keys either.
The BT/IR200 series of remotes, does not pair with other devices, but they have 4 keys which can "learn" IR codes from other IR remotes.
The IR/BT100 remotes have 2 keys which can "learn" IR codes from other IR remotes.
What I typically do in cases like this is set my receiver (and I have an old Yamaha myself), to about the 60% position (which would represent the max volume I would ever use), and then disable the "force max volume" option, so that way the volume buttons on the BT400 remote actually control a variable volume level from the box itself. So when the box says 10%, 50%, etc.. of volume, that represents a proportion of the max level you have already dialed in on your receiver.
I know it may not sound convenient, but at least this way, you only need to set a volume once on your receiver, and then the rest of the time, you can control the volume from your Buzz box remote.
PS: If you have already tried to pair/program the BT400 remote, you may need to just do a factory reset on the remote.
If you wish to factory reset your remote to erase all settings press
and hold the D-Pad Down button and the 0 (Zero) button for 4
seconds until it blinks 3 times to indicate the remote is factory reset
BT300/400 remote manual:
https://buzztv.com/wp-content/uploads/2022/07/BT400-300_manual_MOBILE_v6_Compress.pdf