For convenience, buy a 3 sim from Amazon in the US before leaving.

https://www.amazon.com/PrePaid-destinations-including-European-countries/dp/B01FI1JW72

https://www.amazon.com/dp/B01FI1JW72/

Use this SIM card in your current phone and make calls using the hangouts app so you can continue using your Fi number for calling.

All of those countries are covered by that plan. You can also activate and use the sim in the US on ATT and T-Mobile.

There is no cap on video but personal hotspot won’t work while in the US. It should work fine once you arrive in Europe. If you need more than 12gb data, you can buy two SIM cards.