Name
Rayd
Race
Human (Isekaied)
History
From a planet far, far away from our Earth where the hit game Raid Shadow Legends took off and become the leading monopoly on it. The game growing to large it has everyone on the planet playing, the advertisers of yore are recognized for their role in bringing the company and game to such renown and fame.
The conglomerate owning the game setting its sites on extra terrestrial life. They have hired and trained those that lack the funds to spend on Raid Shadow Legends into ambassador and advertisers.
Rayd (self named) grew up playing Raid and has always dreamed of being like the advertisers of yore... after years of study, both in playing and advertising he was ready to go out into space and show the aliens the best game ever created and give them free character draws. (or something, I haven't played...) But on his first day on a known as Earth in year 2017 he was hit by a truck not long after leaving his flying saucer. Rayd was knocked unconscious and when he awoke on his deathbed he gave his well practiced last words "RAID: Shadow Legends

is an immersive online experience with everything you'd expect from the world dominating RPG title. It's got an amazing storyline, awesome 3D graphics, giant boss fights, PVP battles, and thousands of never before seen champions to collect and customize..."
After his death Raid Shadow Legends as we know it was spread to that world and for his efforts he was isekaied into your world.
Appearance
A born in Canada he modeled his looked after 2020s youtubers (I... also don't really watch YouTube so... uh)
He was 21 by the time he died, but may have been reincarnated differently, not sure how your world works.
Personality
A young mind that views himself as a shonen protagonist would, thinking he can change the world and compares himself to legends, dreaming of reaching higher than they did. Addicted to reading, writing and sharing his ad reads. Rayd has lived his life studying the game and is as such very critical when it comes to optimising and competitive to a flaw.
Abilities
Trained in various forms of communication, language and space travel in order to spread Raid Shadow Legends.
While Rayd has no real combat experience or ability he is a genius when it comes to Tactics, even more so Raid Shadow Legends where he managed to become a top player when studying.
Soul Keeper
A tablet which has a special version of Raid Shadow Legends in which he can summon into the real world character from the game.
Not sure but you could;
1. Give him his account from before his Isekai.
2. Give him the ability to strengthen his characters as you normally do in game.
3. Have it based on mana cost and he can create any character or boss from the game.
Finally, he needs to be able to boost his summons even farther when advertising Raid Shadow Legends.
This is the basis of all his strength.
(Cool things he could do in a fight)
Start doing ad reads and give himself free characters buffs.
Convince people to play Raid Shadow Legends and win, either beating them in game, or them wanting to support Rayd in spreading the game.
If nearly losing, summon every character, ie thousands of heroes, dragons, demons and bosses.
...I don't know I haven't played the game.