SmartMX1 (P5 series) is a dinosaur. SmartMx2, the successor, was introduced in about 2010 and it is at P71/SmartMX3 now.

SE050 is similar to the Infineon Optiga ones. Both are better than ATECC.

The problem is there is no SEs supporting Bitcoin algorithms, or content-aware signing (so you can for example block a Request to Vanish event from ever being signed)