Cloudflare Pages 308 redirects - what's best to go in the canonical tag and xml sitemap?

I’m thinking of moving a site onto Cloudflare Pages. The site currently uses .shtml as it's been around for 20+ years and in 2000 SSI were the way to do includes!

I'll be going changing over to .html and will be using 301s to redirect the pages, etc.

BUT - Cloudflare Pages also uses auto adds 308 redirects on .html endings, so /foo.html becomes /foo.

So, what’s best to put in the 301s, canonical tags and xml sitemap?

/foo.html (as the file will be) or /foo (which the user/search engine 'sees')?

And... would it be best to update internal links to remove the .html(s) to save extra redirects?

Thanks!