My current, October 2019, WP set-up is:

Theme: Sempress (with adaptations in a child theme I created)

Plugins:

• Akismet Anti-Spam
• Bridgy, for posting to Twitter from my site (and through the Brid.gy service getting back-feed from Twitter and Mastodon). I should be using Syndication Links as a replacement, but haven’t installed that yet.
• Category to Pages WUD, to add categories to pages, which I use to make my 1-man ‘wiki’
• Classic Editor, as some of the IndieWeb plugins don’t work with WordPress block structure, so I retain the old posting interface
• IndieAuth
• IndieWeb
• Mastodon Autopost, to post to Mastodon from my site
• Micropub, to allow me to post to my site using various clients such as Indigenous on my Android
• Post Kinds, to create different types of postings, including likes, bookmarks etc.
• Posted Today, to create ‘on this day in …’ lists of my older posts
• Postie, to post on this site by sending an e-mail
• Semantic-Linkbacks, to present mentions, likes etc from others in a nicer way
• Simple Location, allows me to add locations to postings. Don’t actually use it.
• Ultimate Category Excluder, allows me to keep specific categories on/off the front page, in/out the RSS feed, search or archive overviews. I use this a lot, creating different content streams
• WebMention, to let other sites know I link to them, to hear from other sites they link to me
• WebSub, not sure why I’m using it or what it does
• Widget Context, to keep some widgets off single post pages as they interfere with correct microformats interpretation (machine readability)
• Wordfence Security
• Yarns, a microsub server. Not actively in use yet. I’m trying to set-up one of my existing WP test site as my microsub server. As I don’t want all my feed subscriptions in my live site’s WP database. So ideally I have the subscriptions in another site, while interacting with them from this site.

Ten of these plugins are IndieWeb related, and form a collective block of functionality.