Here are some good Jain-friendly boy names starting with “De” (many are based on Jain Tirthankars, Ganadhars, or virtues):

1. Devendra – Lord of devas (heavenly beings)
2. Devansh – Part of the divine
3. Devesh – Lord of the gods
4. Devraj – King among devas
5. Devang – One with a divine body / part of divinity
6. Deval – Holy, divine
7. Devak – Divine, god-like
8. Deveshwar – Supreme Lord (used for Arihant/Paramatma in bhakti)
9. Deeptansh / Deeptanshu – Part of light, radiant
10. Deeptesh – Lord of light, one who is bright
11. Deenank – Day-giver, related to time/light
12. Devit – Derived from “Deva”, divine
13. Devrit – One who follows the divine path

If you tell me your preference (short/modern/traditional/linked to Tirthankars, etc.), I can suggest a more focused list.