The only way to trust this is them selling "cloud compute" servers that folks can deploy and monitor in their own infrastructure. Nothing else can be guaranteed to not include malicious code to exfiltrate the data.
Or better yet, make the APIs public and pluggable so that one can choose an off-device AI processor themselves if one is needed.
Your own infrastructure is definitely less secure than this or even, say, Google. You do not have the capability and teams of SREs to detect intrusions, and an attacker would know that your server processes your data.
Maybe, but I can totally firewall my own servers to my heart's desire, including completely blocking it off from the internet and only allowing connections via my own network's routes.
I VPN (WireGuard) into my home network to access other selfhosted services (like Immich for photos, paperless-ngx, DNS adblock, etc.) and to prevent some tracking, so it would work great for me.
Or better yet, make the APIs public and pluggable so that one can choose an off-device AI processor themselves if one is needed.