Question about digitec connect Voucher for 12 months of with unlimited data

Yes, it works very well in a mobile router. I have been using it in this combination for a few months now and am very satisfied so far. As long as you have a fairly normal consumption and do not make static downloads/uploads or need the part commercially, this subscription is very well suited for use with a mobile router.

Watch out for the speed. When such subscriptions are operated in routers, the speed is sometimes throttled....

In principle, yes. However, you might be better off with an IOT data SIM from Digitec:
digitec iot Daten Flat (30 days unlimited 10 Mbit/s)
10 CHF per month --> 120 CHF per year