[bear8642]

> the only relevant big-endian architecture is s390x

The adjacent POWER architecture is also still relevant - but as you say, they too can afford a support contract.

[AKSF_Ackermann]

The adjacent POWER architecture seems to be used in ppc64le mode these days.

[classichasclass]

For Linux, yes. AIX and IBM i still run big.

[namibj]

The latter can definitely afford a support contract.