Turn my Nexus 5 into a Google Home device

A

AC Question

So....plenty of smart people on here.

I have a Nexus 5 that lost its cell signal forever. Nice little tablet now. I'm in desperate need of Google Home device for my home. My wife has memory problems and would greatly benefit by a Home-like device that she could simply speak out and say, "Ok Google. Remind me in 10 minutes to turn off the stove". She need 100 reminders like this in a day.

Google Now works pretty well. I love it. Fun to use in front of Apple fans and have them unanimously say, "Wish Siri worked like that." Why wait for a Google Home. I'm looking at a splitter for the headphone jack on my Nexus 5 and some regular speakers. I think I need a better (perhaps powered) microphone that could pick up a voice from across the room. Any suggestions? Anyone done this? Would like to not spend hundreds of dollars on a fancy microphone.