Well, i can explain how i did, but i can't guarantee that the game will work until the end without issue, because i have to play/test myself with Goldberg Experimental steam client.

So here is:
1. Download demo via steam, then launch it once to get denuvo token.
2. Copy from full game : the .pak files required to the demo folder (aka bypass method, i won't explain again)
3. Copy "1223730" folder (demo denuvo token inside) from C:\Program Files (x86)\Steam\userdata\*********\
to C:\Users\*User_Name*\AppData\Roaming\Goldberg SteamEmu Saves\ (create this folder manually if it doesn't already exist)
4. Add your user steam id (your real because denuvo token is tied with it, you can find it inside steamapps\appmanifest_1223730.acf -> LastOwner)
to C:\Users\*User_Name*\AppData\Roaming\Goldberg SteamEmu Saves\settings\user_steam_id.txt (create manually if it doesn't already exist)
5. Download Goldberg Experimental steam client here (Latest Build From Git): https://mr_goldberg.gitlab.io/goldberg_emulator/
6. Extract Goldberg .zip and Copy all files from "experimental_steamclient" folder ONLY to Trials of Mana Demo\Trials of Mana\Binaries\Win64\
7. Edit ColdClientLoader.ini : Exe=Trials of Mana-Win64-Shipping.exe and AppId=1223730
8. Launch the game with steamclient_loader.exe and play offline without steam.
[Optional] you can block Trials of Mana-Win64-Shipping.exe in your firewall.

PS: save location: C:\Users\*User_name*\Documents\My Games\Trials of Mana\Steam\

Good luck.

これだろ和訳してやったがだめだった
まあSWITCHでやってるからいいが