I'm trying to build this Ethereum hardware wallet on a custom designed embedded system and I'm no expert. Googling around I found this Robust, low-cost, auditable random number generation for embedded system security paper. As I read the proposal in this paper, it sounded quite safe; a real TRNG. Neverthless, as I struggled to simulate the circuit in any online circuit builder, I thought that maybe I didn't need that much of a complicated system. Maybe using some sensors (humidity, light, vibration, sound) I could gather external data, use it to seed a PRNG and it would be safe enough. But I'm no expert neither in cryptography nor in private key generation practices.
What do you think? Is it reasonably safe enough to use simple external sensors to gather entropy and seed a PRNG? Or should I build this TRNG no matter the struggle? What are the drawbacks of using one over the other? What are the benefits?