Seeking Advice - Tahiti Phone Data Service for Travel with US-Mobile Plan

Hello, I was seeking advice regarding data coverage in Tahiti based on my inquiry below from a T-Mobile sub. Is it best to just purchase an esim before my trip from the local carrier? Thanks in advance for any help or input.

From post:
Hello, I am a current T-Mobile unlimited customer paying $65 a month. My service is very poor in my home and work areas, and I use a $10/mo US-Mobile Warp (Verizon Tower) 5GB sim for additional coverage (standalone prepaid data).

The Warp/Verizon service is much better and I was considering switching the the USM $44 Unlimited plan. I also have an ongoing unresolved issue with TMO's Visual Voicemail service no longer working, and support was unable to help (blamed it on Samsung/Android updates).

I would like to port/retain my TMO number and the USM rep said that should be seamless, but could only be hindered if TMO delays allowing the number to be switched. I am wondering if this can be a pain, or if it's typically pretty seamless. Also not sure if TMO may try to charge any "exit" fees if I cancel with them.

I did have one concern that I will be traveling to Tahiti (French Polynesia) in May. This country is not offered in any of USM's international standalone roaming add-ons (usually $15 for 1GB or $45 for 5GB). From what I Googled, TMO does offer coverage in Tahiti. Perhaps I could get around this by purchasing a local carrier esim prior to the trip.

To note, with my current TMO plan, when I travel internationally, I do still purchase the $35 10-day add-on to ensure that my data speeds are the fastest possible.

Also seeking general advice if switching plans may be more trouble than it's worth although it does sound attractive. I appreciate any additional advise or context.

I have an older Galaxy S21 Ultra phone that suits my needs. I guess the only rationale to stay with TMO would be potential steep discounts for a new device, but I can't see myself wanting to commit to two years of payment as the phone discount amortizes. Perhaps I'll just stick to buying devices directly from Samsung or Amazon.

To summarize, I pay $65 for TMO (w autopay) and $10 for addl 5GB USM data (enough monthly data for me so far). Total $75 a month (taxes included within that price). I need to purchase the $35 international packages for trips.

USM would be $44 (taxes extra?) and I'd need to purchase the occasional $45 data plans for international trips. The improved Warp/Verizon service would likely omit my need for a Lightspeed/TMO second sim to fill the coverage gaps.

Really appreciate any advice or input. Thanks in advance for any help.