I made progress by installing DOM (pkg install php74-dom) and then some Googling led me to investigate the issue with TokenParser.php. It transpires that I also needed Tokenizer (pkg install php74-tokenizer) to deal with that issue.
Following that, I am still getting the blank page at Document Root http://192.168.10.23/ but the CLI runs and does the SuiteCRM install.
Post install, I still get the blank page at Document Root. It seems that the index.php is looking for ~10.23/api/graphql which is not in the directory structure.
I hypothesize that it could be a rewrite path and that my rewrite isn’t working as expected.