So here's what we do in Europe, but the solution should work anywhere the local networks are fast enough to carry a VoIP call, which isn't a high bar:

US numbers ported to Google Voice and used via data (Hangouts) while outside the US. $10 once to port the number, free to call or SMS the US.

Whatever local mobile service meets your needs.

A new Google account with Fi, which we keep paused unless one of us is travelling to the US, at which point we resume the service. Our respective GV accounts still work via data while in the US (you can't forward a GV number to Fi). The new Google account serves two purposes--first, you can't have Fi and GV on the same account; second, multiple people can share the new account.

If we're both in the US at the same time, one of us takes the real SIM and one takes a data SIM. If your phone supports eSIM, you can even skip the paperclip and use Fi via the eSIM.

I know people who keep Fi active all the time, but that's a waste of $20/mo + data in my opinion*. I also know people who just keep T-Mobile US accounts active in Europe and pay $70/mo for 256kbps data, which is completely insane.

*because even in Belgium, land of ineffective competition and overpriced everything, we get 4GB/mo for €15.

Two other potential options:
If your phone supports eSIM, another option is to just buy short-duration data-only eSIMs for your trips back to the US, e.g. Airalo's $3 for 1GB over 7 days. This is even cheaper than resuming Fi.
Depending on where you're going, if your carrier offers US roaming for free or cheap, just use that and skip Fi altogether. I've been using a French plan that includes US roaming for the past few months, which makes life easy. Ping times are terrible, as expected, but data speeds are on par with using an American SIM.