Query Regarding Play-Time tracked...

Don't know about family sharing play time, but I know that free weekend play time doesn't reset after you purchase the game... so family sharing might be the same.

No.
The playtime will remain, no resetting, no starting over.
I know it 100%, cause I've played some games via family sharing.

Nope the playtime remains and is bound to the account forever, even for games that are not owned but family shared. ;)
You cannot reset playtimes.

No it won't reset. Played Slay the Spire for about 48 hours through Family Sharing before I got the game myself, those hours were still there. Same goes for other games, still have the hours in them while FS isn't on anymore now (because it turned itself off or something)

Cool, thank you so much for clarifying guys! 😁