As documented in An R Markdown output format for blogdown web pages — html_page • blogdown the highlight parameter is passed to bookdown::html_document2() with no further processing. So you should be able to pass a Pandoc highlight theme like tango or pygments. If it does not work, this could be because of something else. Maybe it conflicts with the Hugo theme used.
It seems like the blogdown::shortcode function is not perfectly compatible with setting attributes on highlight shortcode.
You can do this probably to make it works
blogdown::shortcode_html("highlight bash", linenos = "inline", .content = "cd .. && ls")
{{< highlight bash linenos="inline" >}}
cd .. && ls
{{< /highlight bash >}}
I don't know how that would behave within blogdown::html_page format, but I let you try and tell me 