Cap is the only dude who knows how to use the shield. Falcon doesn't have the skills or the strength to use it. If you're going to give it to Falcon, at least melt it the fuck down and turn it into something he can use.
Well, first and foremost, Sam would be using it effectively
enough ... By using the shield as a shield.
It looks to me that the series is giving Falcon a character arc that ultimately leads him to earning the shield (in his eyes), which is what the show
should do if it's any good. I'm hoping that's the case, and that the show doesn't suck (and if it does suck, I'll definitely say it). We'll see soon enough, I guess. The training sequences that have been shown in the trailers are promising.
I still think that Sam deserves the shield more than Bucky. Firstly, Bucky could very well still be a liability due to his brainwashing. Secondly, it would be weird optics to say the least if The Winter Soldier became the next Captain America. Bucky had been in hiding post-Civil War and then "died" in Infinity War; as far as we know, Bucky is still
very much an enemy to several world governments.
Steve gave Sam the shield because of his values and his sacrifices: Sam became a superhero/Avenger when he helped Cap in The Winter Soldier and then became an outlaw in Civil War for Cap ... All because he held the exact same values as Steve. If anyone adores, respects, and appreciates what Captain America means to the world, it's Sam.
At the end of the day, isn't it a much more interesting story to see a character
work for the shield and the title of Captain America, rather than another super soldier using the shield easy peasy? Steve was the underdog in The First Avenger, and if this show plays their cards right, then Sam will be one as well.