Should I buy a Bird diaper+leash or a bird harness/leash?

Im worried whether my cockatiel will like the diaper or not! I think it’ll be easier for him to get used to the harness. I know that the harness is escape proof but wat about the diaper, if my bird flies or for some reason tries to escape will it slip open?
And can I get the both of these in any bird store in Atlanata (USA)?
And which brand should i get, which is the most escape proof and comfortable for my bird?

I would get the diaper and leash more, with the harness birds tend to get loose or strangled because it has more holes.

Actually, my own cockatiel hated the harness and tried to take it off constantly, it was too heavy. The diaper was a little better but he still tried to take it off.

I wouldn’t recommend using any of those, birds should be free and ones that aren’t trained from hand feeding to wear them will never get used to them.

Baby Cockatiel & Bird Harness