The post of @Mr.E who has applied for citizenship (Portuguese Citizenship application after 5 years of Golden Visa - #226 by Mr.E) gives recent data on what was required for his application for proving connection. The requirement is minimal, at least for adults.
The citizenship law was amended in mid-April 2022: https://dre.pt/dre/legislacao-consolidada/decreto-lei/2006-34442175-180718705
See also an analysis of the change by sm33 Portuguese Citizenship application after 5 years of Golden Visa - #115 by sm33