This is a long shot but I still am baffled as to why I never recieved my sprays that I put in time for. I really am hoping that this could maybe be a glitch and some tech god can fix this but I’m still at a loss.
And before being asked if my accounts were properly connected they indeed were as I recieved all the skins via Heroes of the Storm way back when.
Unfortunately it is very late to inquire about it now if you never received credit for the twitch rewards during the Pink Mercy promotion. It sounds like you properly linked your Blizzard account to a console account, but remember that with Twitch promotions your Blizzard account must also be linked to a Twitch account to receive those rewards.
During Twitch promotions (which none are currently running at this time), I maintain a guide that troubleshoots common causes for not receiving Twitch drops from eligible streams such as Overwatch League. So if and when the next promotion comes around, check it out if you are having problems earning future items.