Why might you find yourself praying to your deceased grandmother rather than to Christ? Because in your story she is another Christ, not an alternative Christ.
As a scholar of medieval liturgy and culture, I know that there has been a long history of including children among the saints approved for official recognition and veneration.
In his exhortation on young people, “Christus Vivit” (“Christ Lives”), Pope Francis said Acutis was a role model for young people today who are often tempted by the traps of “self-absorption, isolation and empty pleasure.”