# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(?<!\s*[=]\s*\d+)\,\s?(?![^\<]*\>)/\n/g;t' <<< "<product_11,product_12>=5,product_1,product_2,product_3=1,product_9=3,<product_5,product_6>=10,product_11,product_12,product_13,product_14=20"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html