Here are some simple Jain-friendly boy names starting with the letter P:

• Parshva / Parshvanath – Name of the 23rd Tirthankar.
• Prabhav – Brightness, influence.
• Prakash – Light, radiance.
• Praveen – Skilled, expert.
• Pranav – Sacred sound/mantra.
• Prashant – Peaceful, calm.
• Pratap – Courage, glory.
• Praful – Blossoming, like a flower.
• Punya – Merit, virtue; doing good karma.
• Piyush – Nectar, something very sweet and pure.
• Pankaj – Lotus; purity.
• Pragyan – Wisdom, good understanding.

You can see a related list here