As Snowden told us, video and audio recording capabilities of your devices are NSA spying vectors. OSS/Linux is a safeguard against such capabilities. The massive datacenter investments in US will be used to classify us all into a patriotic (for Israel)/Oligarchist social credit score, and every mega tech company can increase profits through NSA cooperation, and are legally obligated to cooperate with all government orders.
Speech to text and speech automation are useful tech, though always listening state sponsored terrorists is a non-NSA targeted path for sweeping future social credit classifications of your past life.
Some small LLMs that can be used for speech to text: https://modal.com/blog/open-source-stt
I googled the echo flex and I don’t see any evidence someone has gotten the bootloader unlocked or have been able to install a custom ROM/OS. Depending on the generation the flex is based on, it could be Linux or android based. Have you been able to access the os on your devices? If not, you might have a lot of work on your hands to get enough access to install any kind of non-stock OS.