Personally if you're looking for something no more complex than Medium I'd just use the WordPress.com paid plans. No membership or sign-in required for your rea

Personally if you're looking for something no more complex than Medium I'd just use the WordPress.com paid plans. No membership or sign-in required for your readers and pretty much anyone who has worked in blogging has a knowledge of WordPress. If you're willing to put in the effort and try something new I'll second the Forestry/Netlify approach above with the caveat that it might still require some training if you want to do anything fancy.