You can convert text strings like
2/3 in column
A2:A into decimal numbers like
0.666 like this:
=arrayformula( iferror( regexextract(trim(A2:A), "^(d+)") / regexextract(trim(A2:A), "(d+)$") ) )
In the general case, there is not much point to try and implement a parser to evaluate a text string as a spreadsheet formula. It is much easier to use the initial
= and let Google Sheets do the hard lifting.