[866-RON-0-FEZ]

> to pre-heat or pre-cool the car remotely before going to work, while it is still plugged to the wall charger

Modern aftermarket remote start systems work with both ICE and EVs alike. Take a look at Compustar. You can remote start your Leaf with a key fob from 1/2 mile away, no telemetry, connectivity, or silly app needed.

[ThinkingGuy]

There's also OPVS, which supposedly can be self-hosted (I don't know how good their product is; I'm content with 3G-only 2012 Leaf being permanently offline).

https://www.openvehicles.com