This white paper (WP) presents a comprehensive analysis of how 27 projects funded by the SNS JU address sustainability in their work on next-generation (6G) communication technologies. The analysis draws on detailed questionnaire responses and follow-up interviews, spanning four core themes: (i) sustainability targets, (ii) methodologies, (iii) trade-offs, and (iv) implementation considerations. The insights presented reflect the diversity of approaches, opportunities, challenges, and emerging trends across projects operating primarily at low to mid Technology Readiness Levels (TRLs).