Provide a searchable transcript/datadump on your website.
Outer Wilds came up in the comments as a game that is designed to be played without a wiki because it has a great in-game log. However, while OW is played without a wiki, it doesn't mean it doesn't need a wiki.
JMac: It might be interesting to look at something like Outer Wilds. The game provides a way to track of what you've found/done, so it's fairly easy to remember what is going on. Yet because of the structure of the game, people are adamant (maybe too much) that you shouldn't look anything up outside the game.
Outer Wilds nevertheless has a fandom wikia. When I've used this, it's because I'm talking about the game and am unable or unwilling to launch the game, fly out to a planet, and find the appropriate text/screenshot for myself.
Since making a wiki takes a lot of time and effort, if there's already a complete catalogue that your experienced players can refer to, they won't take it upon themselves to make one.
(I wouldn't require having the game installed, either. I understand there's some concern of "Why would anybody buy my game if they can just open up the transcript and read it?" but the same applies to watching a let's play. Having a bog-standard website means your players can link to it, reference it on their phones, etc.)
Make your own wiki/guide and ask the community to use/recommend it.
Somebody is going to reach a point in your game and search "[gamename] guide level 4". If you want to control how spoiler-y the guide they come across is, take the first spot in the search results yourself. If you're building an in-game "wiki" application, you've already got all the writing done--paste the contents online with appropriate ordering and spoiler tags.