> More and more I find I'm using gmail for my store of knowledge.
While I think Mail is a possible way to store knowledge, I try to prevent google wherever possible.
> I suppose your blog is searchable via google though.
No, it is a static json file with some lines of javascript. If you would like to know how to build a blog like this, here is an article about it: https://pilabor.com/blog/2021/05/building-a-blog-with-hugo/ :-)
> For example, the instructions for renewing my let's encrypt cert pop up in my inbox every 2 months in an email reminding me to do it.
I follow a pen and paper approach for my daily tasks. And I try to automate everything, letsencrypt can easily be automated.
> If I order something online I snooze the confirmed order email to some date in the future to remind me I should have received it, etc.
This is a nice idea... thank you.