iPhone eSIM temporary unlock while traveling abroad

HI,

I would like to know if eSIM can be unlocked only while traveling abroad.

We used to be with another carrier "V" as I heard they were the only one keeping the devices unlocked even while the phone is in installment.  We switched to T-Mobile 9 months ago because T-Mobile sales representative offered cheaper monthly fee for seniors like us, upgrade to iPhone 15 and T-Mobile unlocks SIM temporarily for 30 days if requesting before traveling abroad even we are in equipment installment plan.

Today I contacted for T-Mobile chat support as my wife is traveling to Japan from this weekend and was advised by a chatbot that we are not eligible to unlock because there is a balance for monthly device payment.

I googled and read some people saying the temporary unlock is available only to Android phones.  It seems to be not what T-Mobile does/doesn't but rather hardware setting on Android.

I also see certain iPhone can be unlocked only if installment plan is purchased from Apple store or Apple.com, which sounds weird to me why customers purchased directly from the carrier is limited in services.

Although my Go5GPlus plan offers up to 5GB data included, I was informed I need to purchase international data pass after that ($35 for 5GB in 10 days, $50 for 15GB in 30 days), which sounds comparably expensive as long as I researched Japan local carriers’ prepaid data rate.

We travel overseas only 1 or 2 in a year, so it is still cheaper when considering the monthly charges overall, but I just would like to know the correct information of iPhone under T-Mobile equipment installment plan.   Could someone who was recently in the same situation or T-Mobile expert could clarify the most updated information?   Thank you so much,