I don't think I have any background IR, even in raw mode I only see data when I am actually using a remote controller. I have the lambda working, I think, using the following (I tried to make the repeat/times/wait dynamic and then gave up and just set it to 5/10ms):
api:
  services:
    - service: send_pronto
      variables:
        data: string
        times: int
        wait_time: int
      then:
      - remote_transmitter.transmit_pronto:
          data: !lambda 'return data;'
          repeat:
            times: 5
            wait_time: 10ms



This is what I see when I capture a single press of the actual remote Power Off button:
[10:46:27.517][C][mdns:177]:   Hostname: esphome-web-803804
[10:46:29.460][D][remote.beo4:086]: Beo4: n_sym=68
[10:46:29.463][I][remote.pronto:229]: Received Pronto: data=
[10:46:29.463][I][remote.pronto:237]: 0000 006D 0022 0000 015C 00AC 0017 0015 0018 0014 0018 0014 0018 0014 0018 0014 0017 0014 0017 0014 0017 0014 0018 0040 0017 0040 0018 0040 0017 0040 0017 0040 0018 0040 0017 0040 0017 0040 0017 0040 0017 0014 0017 0040 0017 0040
[10:46:29.477][I][remote.pronto:237]: 0017 0040 0017 0014 0016 0041 0017 0015 0017 0014 0017 0040 0016 0015 0017 0014 0017 0014 0017 0040 0017 0014 0017 0040 0017 0180
[10:46:29.498][I][remote.pronto:229]: Received Pronto: data=
[10:46:29.501][I][remote.pronto:237]: 0000 006D 0002 0000 015C 0055 0017 0180

Pressing and holding is slightly different

[10:50:04.540][D][remote.beo4:086]: Beo4: n_sym=68
[10:50:04.553][I][remote.pronto:229]: Received Pronto: data=
[10:50:04.554][I][remote.pronto:237]: 0000 006D 0022 0000 015D 00AB 0018 0014 0018 0014 0018 0014 0018 0014 0018 0014 0018 0014 0018 0014 0018 0014 0018 0040 0018 0040 0018 0040 0018 0040 0018 0040 0018 0040 0018 003F 0018 0040 0018 0040 0019 0013 0018 0040 0018 0040
[10:50:04.567][I][remote.pronto:237]: 0018 0040 0018 0014 0018 0040 0018 0014 0018 0014 0018 0040 0018 0014 0019 0013 0018 0014 0018 0040 0018 0014 0018 0040 0018 0180
[10:50:04.602][I][remote.pronto:229]: Received Pronto: data=
[10:50:04.603][I][remote.pronto:237]: 0000 006D 0002 0000 015C 0055 0018 0180
[10:50:04.723][I][remote.pronto:229]: Received Pronto: data=
[10:50:04.727][I][remote.pronto:237]: 0000 006D 0002 0000 015D 0054 0019 0180
...
[10:50:05.473][I][remote.pronto:237]: 0000 006D 0002 0000 015D 0055 0018 0180
[10:50:05.575][I][remote.pronto:229]: Received Pronto: data=
[10:50:05.576][I][remote.pronto:237]: 0000 006D 0002 0000 015D 0055 0018 0180


And this is the feedback I see when I send the data over the transmitter (which leads me to believe at least the hardware and my integration with HA is OK?)


[10:47:02.657][D][remote.pronto:102]: Send Pronto: frequency=38kHz
[10:47:02.657][D][remote.pronto:107]: Send Pronto: intros=4
[10:47:02.658][D][remote.pronto:108]: Send Pronto: repeats=0
[10:47:02.692][I][remote.pronto:229]: Received Pronto: data=
[10:47:02.696][I][remote.pronto:237]: 0000 006D 0002 0000 015E 0053 0019 0180
[10:47:02.726][I][remote.pronto:229]: Received Pronto: data=
[10:47:02.737][I][remote.pronto:237]: 0000 006D 0002 0000 015E 0053 0018 0180
[10:47:02.758][I][remote.pronto:229]: Received Pronto: data=
[10:47:02.759][I][remote.pronto:237]: 0000 006D 0002 0000 015E 0053 0018 0180
[10:47:02.794][I][remote.pronto:229]: Received Pronto: data=
[10:47:02.794][I][remote.pronto:237]: 0000 006D 0002 0000 015D 0054 0019 0180
[10:47:02.812][I][remote.pronto:229]: Received Pronto: data=
[10:47:02.815][I][remote.pronto:237]: 0000 006D 0002 0000 015E 0054 0018 0180

I'm reaching with assumptions here, but it seems as if the actual remote is sending a preamble code that is interpreted as BEO prior to sending the multiple commands (every button seems to do this with no variation from n_sym=68; only the code that follows this varies).
Any idea how to deal with that? Or am I going down a rabbit hole of ignorance haha? I was thinking maybe I need to first send the BEO code to open the connection and then repeat the actual code (which, is slightly different each time? is that just error, or is it intentional??)
Thanks for the input so far, much appreciated