Do we know if there are speculative execution attacks that affect ARMv7 CPUs at this time? Are there any theoretical risks that need further investigation?
ARMv7 is a version of the ARM CPU specification, not a specific CPU design.
Some ARMv7 implementations, like Cortex-A15, make use of speculative execution and are affected by the Spectre vulnerability. Others, like Cortex-A5, do not implement speculative execution and are unaffected.
For details on which ARM cores are affected and what mitigations exist, refer to: https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability