I'm using the traccar client integration in HA and the traccar client on my phones.
So, I don't have traccar server anywhere.
This allows me to use the webhook URL from the traccar client integration on HA and use a web proxy to protect that from the internet.
On the phones, the traccar client connects to the webhook URL I expose through the proxy.
Hope that makes sense as everything is called client here - took me a while to work it out myself.