Good news first,
@jbodnar - unlike the Bosch ConnectModule, there's no Avinox subscription to pay.
Unlike Bosch, everything is included, and there's no need to subscribe to access the full range of features - your only ongoing cost is the SIM itself, which can easily undercut your $35/year Vioma setup.
What to buy: a cheap prepaid
nano-SIM with a small data plan from a major US carrier (or one of their MVNOs). The data needs are tiny - remote control enabled: approximately 200MB per month, ride data upload enabled: approximately 200MB per month - so ~500MB/month covers it, and the cheapest prepaid data plans in the US run a few dollars a month. Given where you ride in SoCal, I'd lean toward whichever network has the best coverage in your actual riding zones rather than a specific brand - the bike's modem is only as useful as the signal at the trailhead.
Two things to avoid, straight from Amflow/Avinox support: • They do not currently support IoT SIM cards, and suggest avoiding roaming SIMs if you're riding long-term in one country - so skip the Hologram-style IoT offerings and travel eSIM-converted cards; a normal consumer prepaid SIM is the safe bet.
• 4G features are not available during data roaming, which is why cheap international roaming SIMs fall over.
Setup notes: the SIM installs behind the control display, then you enable Bike Connectivity (SIM) in the Avinox Ride app. If it doesn't connect first go, some configuration may be required - the APN settings are in the Avinox app under Cloud, then "Configure APN Settings". Not all SIMs play nicely; there's no official US-confirmed carrier list I can point to yet, so keep the receipt and be ready to swap if the first one sulks.
One caveat worth checking on your RS 181.2: the Avinox DPC100 Control Display (Global) does not support 4G connection - only the DP100 touchscreen takes a SIM. Swipe up on your display settings or check with Crestline which display yours shipped with before buying anything.
What it gets you once running: even with the system off, you can check battery level and location remotely, plus theft alerts and ride sync - genuinely more than the Bosch module offers, for less money. Hard to grumble at that.