Really enjoyed the video. Inspirational!
I think you are way fitter than you give yourself credit for! Your ambition or enthusiasm is awesome, but that has a detrimental effect to your pacing! My advice (hope you don’t mind) would be to forget about maximum power as that can actually work against improving fitness and weight.
It might be useful to do an FTP test to help with pacing so you are not going off too quick all the time. We have all been guilty of that! In the beginning it feels like you are going to easy at the start of every ride, until you realise that you are way more comfortable and feel strong, sometimes stronger and stronger as the ride goes on.
After a while, it will become second nature and you will enjoy riding so much more!
It’s great that you have the HRM so that you can do recovery rides where you stay in zone 1 and 2. Easier rides should make up the majority of your time on the bike, but they are harder to do than fast rides in the beginning, because we falsely believe there is no benefit without pushing ourselves.
There is loads and loads of available information about this, but you probably know already!