Why are you so obsessed with the chess press?If you have the tennis_balla quote I'd like to see it. I analyzed his backhand video some years ago but can't locate it.
This following post gives a list of the one hand backhands in the ATP. There is also a slow motion video with clips of 14 ATP top 100 players with one hand backhands.
I just saw a clear video of Dan Evans's backhand and he can be added to the longer list for straight arm forward swings. Chest press forces are not visible in videos but upper arm on or very close to the chest does show and so does the chest and upper arm moving together in sync. I assume the synced together movement makes the chest press forces very likely and is the closest to proof that we will get until a pressure gage is applied. In addition to chest pressing, I'm sure the back muscles are pulling also.
Add Dan Evans to the "Straight arm forward swings ...." group. Clear video but not ideal as he was under pressure.
See slow motion at 30 seconds.
1HBH evidence post.
You would make a better argument for the chess press by uploading a video of yourself hitting backhands instead of spamming TTW with misinformation.
I'm not convinced that you actually know how to play tennis to any degree of competency.