<p>In particular, lattice-based post-quantum cryptographic (PQC) schemes are believed to be good candidates for increased resilience in the quantum era (e.g., Shor and Grover). Still, most proposed solutions lack full consideration of the practical constraints imposed by resource-constrained systems (limited processing speed, memory, battery capacity, and the sustainability costs of large-scale cryptographic computation). Motivated by this gap, this paper discusses a use case in the form of a practical post-quantum security framework that combines lightweight lattice-based encryption/decryption and key encapsulation/decapsulation, with an evaluation methodology for performance and sustainability. Methodologically, the framework (i) models a quantum-compatible adversary and establishes security goals for limited networks, (ii) creates and tuneshigh-performance lattice-based cryptographic parameters further influenced by classic Kyber/NTRU applied settings, and (iii) demonstrates protocol-level feasibility through simulated network scenarios realised through Contiki-NG and NS-3. Performance is measured in terms of encryption/decryption latency, energy consumption, and communication overhead, and sustainability is expressed through environmental impact indicators (carbon footprint) mapped to the energy consumption of modelled computation/communication, considering device-dependent coefficients and configurable emission factors. The simulation results indicate that the average encryption and decryption times are approximately 120 ms and 110 ms, respectively, and that the average energy consumption is below four mJ on edge devices. The COMMOPs incurs a communication overhead about 72% higher than that of previous classical schemes, but remains acceptable in these three low-power network settings. In sum, the framework we propose is a comprehensive roadmap for scalable quantum-safe security deployment, with an emphasis on the human and environmental challenges outlined above.</p>