I agree that buzzing isn’t probably a great idea as it probably will more likely have negative consequences than positive ones. Buzzing is harder on our lips than playing is and should be minimized for only a few minutes each day, especially if you haven’t done it before. Also, in the beginning, the whole purpose is to loosen things up, relax, play less tightly, etc. Buzzing will, in my opinion, result in the opposite result in most players at the beginning unless you happen to be very lucky.
I spent a lot of time commuting pre-COVID and listened to a lot of YouTube videos by Greg and others in the car and there are some breathing and other exercises he talks through that our doable during listening to those videos.
So much of this is MENTAL, as is playing in general. Plenty to do without the horn. What we’re really trying to do is re-wire our minds and how our body responds instinctively to playing.
Spending time away from the horn is helpful for that.
Playing above the staff doesn’t require physical strength as much as it requires coordination and control over our preconceived notions / desires to tense up and apply pressure where it’s not needed, where it doesn’t help us.
Tension is required in the aperture corners, surrounding the embouchure / aperture–not within the lip muscles forming the aperture itself.
Yesterday, I found myself in the car visualizing playing a G above the staff and using articulations–forming an embouchure and the aperture I envision necessary for that note, using different articulations as I was releasing air. I thought this would be helpful for me as I was finding that my consistency wasn’t good when I was using different articulations, I think I have a tendency to lose focus and tighten up as I begin to articulate rather than keep things open, relaxed, resonant as much as possible.
I think Greg has a video in the course called “the secret lesson” or something like that which he talks about spending time away from the horn in a productive way.
Bon voyage / good luck.