T tap with valve for pex?
Disconnecting and reconnecting those lines will stress the connections and cause them to fail.
It should be simple enough to tap into that 1/4&quot; line using a tee connector as you suggest and then adding a 1/4 inch shutoff valve on the tapline. Following is a link to some inexpensive components but you can probably find them at your local hardware store as well.
https://www.amazon.com/PureSec-Connect-Fitting-Assortment-Package/dp/B07D629S7W/ref=sr_1_1?dchild=1&amp;gclid=CjwKCAiAhbeCBhBcEiwAkv2cYxp0g2lpGx0N-YKN4TircqwGvjwjL7gY2ceOIzEXMkbJnn8we298EBoC6uAQAvD_BwE&amp;hvadid=384443217506&amp;hvdev=c&amp;hvlocphy=9028825&amp;hvnetw=g&amp;hvqmt=e&amp;hvrand=11177684254370804919&amp;hvtargid=kwd-825352349189&amp;hydadcr=8432_9886307&amp;keywords=1%2F4+inch+t+valve&amp;qid=1615744105&amp;sr=8-1