VOIP/SIP shouldn’t be a problem. You can even get a separate account for mobile, if desired. Some VOIP providers have SMS-capability, too.
I’ve been thinking a lot about the data-only SIM option, in combination with a SIP account.
In the U.S., the carriers typically will only issue a data-only SIM for tablets and computers, not phones. It will be interesting to see how they treat the L5’s modem: Do they think it’s a phone? A computer? A car?
If the local carrier won’t provide a data-only SIM, another option, as discussed elsewhere in the forums, is to use an international travel SIM, either a data-only SIM, or a regular SIM (and just forgo use of the included foreign number). The travel SIM gets the benefit of roaming on foreign networks, but without being subject to any device restrictions (presumably).
The trick is to find a travel SIM with cheap or reasonable data costs. I’ve seen a couple of those (and currently have one), but the cost-effectiveness is going to depend on how much data is needed per month. (I myself typically use less than 200 Mb! Lol!)