If Tsuna had real friends who didn't go along Vongola's bullshit and a spine, I see him cutting off the relationship for their safety.
I don't see him accepting the Fake Canon Guardians either, but isolating himself so he won't drag anyone into Vongola for begin associated with him. Vongola would insist on getting him a 'family' and he would tell them to go hang.
"You dragged me into this hellhole of a family, I won't let you do this to anyone else I love. You did this, old man, you ruined my life. I won't let you do this to them." he said pleasantly.
"They have long, peaceful futures ahead of them, you won't hurt them like you hurt."
Reborn would go after the friends, claiming they should be the Vongola's, they would make great assets (aka sacrificial lambs), after his attempts at throwing his own chosen people at Tsuna didn't work.
Nono's attempts to sugar coat it would be blow off. His claims thats 'Decimo needs a family' would be answered with an flat look.
"I already have a family, for all I will never see them again, you took them away from me, don't try to pretend you didn't." he bit out shortly and sharply, burning orange eyes glared in fury.
To never be able to see you loved ones again is tragic and I can see him growing even more and depressed and bitter towards the Vongola and (rightful) blame those involved into forcing him into this (even Dino or Bianchi), bluntly refusing any kind of remotely civil relationship with them, showing open hostility.
Or even going to suicide, so his real Guardians would be free and Vongola would be heirless as a revenge.
Its still better than coming home and finding your best friend's head stuffed into a box. Why everyone forget Nono's sons died gruesome deaths?