I'm checking options myself, and definitely Calibre-Web seems the most popular option to accessing your books from the cloud when you don't want to depend on Google and the like.
I feel like you, instructions for setting it up seem too complicated, maybe the docker route will get easier in the near future, anyway, the link you have provided seems overly complicated because it wants to achieve another integration besides setting up Calibre-Web, I would check first instructions to set up Calibre-Web in Nextcloud, and once I have that running, look for a way to integrate it with my preferred reader app. Calibre-Web is quite complete to skip your dependence with CC, although it has the drawback that you'll need to have access to the Calibre-Web server when you want to use it.
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