I think what the OP wants is simply to generate the wallet (seed phrase) offline on the device.
Searching on google for "generate wallet on Trezor via powerbank"
Google's AI response appears, claiming it's possible, provided you use a powerbank and a cable that provides sufficient power, but further down it states that it's still necessary to connect the Trezor to a computer or Android/iOS device (if using Safe 7) with Trezor Suite. LOL. I didn't understand anything, is it possible or not??? I think the AI hallucinated hahaha

I remember some time ago, an update came out for Trezor Suite where it allows generating the wallet with the internet disabled or through a powerbank, but I haven't found any source that reinforces this.
In any case, if the OP really doesn't feel comfortable starting the device for the first time using Trezor Suite on an online computer, he will have to do the following:
Have a second computer or cell phone, connect the Trezor to that computer, initialize and complete the initial setup (PIN + backup, etc).
If you don't have a second device, just download a Linux distribution (like Ubuntu, Mint, etc) and perform the operations in Live mode (where nothing will be stored on the device's HDD/SSD, only in volatile memory, RAM, etc).
Format/perform a clean reinstall of the OS on the second computer or simply download an amnesic and anonymous Linux distribution like TailsOS, burn the .iso image to a flash drive/SD card. It runs in Live mode and whenever a session ends, all data is automatically erased without leaving any trace. Invalidate the SD card or simply break it.

In any case, it's much easier to opt for an air-gapped hardware wallet like Passport, Coldcard, etc... or a second offline PC (requires in-depth knowledge of self-custody and cybersecurity).
Furthermore, if you choose to use your current computer/mobile device, make sure you don't delete the current OS or any files when using a Linux distribution. In any case, as long as you don't install Linux but only use it in Live mode, you'll be fine. Research everything you do thoroughly.
If you want ultimate security and peace of mind, learn about offline self-custody and air-gapped devices. Don't do anything you don't know how to do, gain experience, watch yt videos, etc.