This app was mentioned in 11 comments, with an average of 1.45 upvotes
This one is very fast and small, if it's just about bitcoin. It's for android. https://play.google.com/store/apps/details?id=com.brentpanther.bitcoinwidget&hl=de&referrer=utm_source%3Dgoogle%26utm_medium%3Dorganic%26utm_term%3Dsimple+bitcoin+widget
Edit: I also use it that way. https://www.reddit.com/r/Bitcoin/comments/5u7jp7/selfcomposed_bitcoin_ticker_instructions_inside
I'm using simple bitcoin widget. Should be exactly what you need, down to tapping it to update. You can set it to transparent too, so it doesn't have to be an ugly box like in the screens.
"Simple Bitcoin Widget" for android is lightweight and fast. https://play.google.com/store/apps/details?id=com.brentpanther.bitcoinwidget&referrer=utm_source%3Dgoogle%26utm_medium%3Dorganic%26utm_term%3Dsimple+bitcoin+widget&pcampaignid=APPU_1_0fp9WMKjCYT2Up7InNAI
Try Simple Bitcoin Widget https://play.google.com/store/apps/details?id=com.brentpanther.bitcoinwidget
https://play.google.com/store/apps/details?id=com.brentpanther.bitcoinwidget
Updated by a single touch.
Checking a few times the day.
Will never sell!
Not a notification, but I use Simple Bitcoin widget for a couple different coins.
https://play.google.com/store/apps/details?id=com.brentpanther.bitcoinwidget
I use this one.
Not exactly what you are asking for but I use Bitcoin Widget. https://play.google.com/store/apps/details?id=com.brentpanther.bitcoinwidget&hl=en
Works great
Just a Simple Bitcoin Widget