The core architectural difference at play is the use of a Secure Element (SE) vs. General Purpose MCUs:
Ledger uses a Secure Element (ST33 chip) which runs a closed-source operating system (BOLOS) because the chip manufacturer (STMicroelectronics) requires NDA agreements that prevent open-sourcing the design and low-level code.
Trezor historically rejected Secure Elements to maintain a 100% open-source stack (firmware, bootloader, hardware design), running on a general-purpose MCU (STM32). The drawback is that physical access allows chip-glitching attacks (e.g. Kraken Security Labs extracting the seed). To mitigate this in Trezor Safe 3, they introduced a secure element (OPTIGA Trust M), but they use it purely as a cryptographic co-processor to lock the PIN, keeping the main firmware open-source.
An audit exposing a Ledger flaw is a massive reminder: Closed-source firmware means 'Don't verify, trust us.' In contrast, Trezor's open-source architecture means anyone can verify the code, compile it deterministically, and audit it themselves. In security, obscurity is not safety.
The core architectural difference at play is the use of a Secure Element (SE) vs. General Purpose MCUs:
An audit exposing a Ledger flaw is a massive reminder: Closed-source firmware means 'Don't verify, trust us.' In contrast, Trezor's open-source architecture means anyone can verify the code, compile it deterministically, and audit it themselves. In security, obscurity is not safety.