Bhagavad Gita, Chapter 9, Verse 23

Even those devotees, who endued with Shraddhâ, worship other gods, they too worship Me alone, O son of Kunti, but by the wrong method.

Even worship aimed elsewhere still lands somewhere real, just not by the most direct real route.

This doesn't dismiss devotion to other gods as worthless, it reframes it as real but indirect, missing the more effective path available. The distinction drawn here is about method, not about sincerity.