I have, after some extreme madness, slightly adapted (and I dare say improved) the github checkout one. My use case is to check out PRs that have had my review requested, so I changed the JQ command to do that (which you may or may not want), but the real masterstroke was adding in previewing the body of the PR with mdv. Key to doing that was switching to null delimited lines.

    gh api 'repos/:owner/:repo/pulls' |\
    jq -c --raw-output -j '[ .[] | select( .requested_reviewers | select(.[].login | contains("your-github-handle-here"))) ] | .[] | "#\(.number)\u0009\(.title)\u0009\(.body)\u0000"' |\
    fzf --read0 --delimiter='\t' --with-nth=1,2 --preview='echo {3} | mdv -' --preview-window=up:80% |\
    sed -n '1s/#\([0-9]\+\).*/\1/p' |\
    xargs gh pr checkout

I did my damnedest to use the unit separator character 0x1F instead of tab in between fields but I could not figure out how to get FZF to like it. It makes me so sad that those characters with absolutely primo spots in the ASCII table and that ACTUALLY MEAN what we use tabs (or commas, or pipes) and linebreaks for don't get any love. Ah well.