Where can I find a replacement app. for Dashboard??
iMac 27″, OS X 10.11
Some widgets can be added to the "Today" view in Notification Center
Use Notification Center on Mac - Apple Support
calculator app will do a one time one way conversion of the calculator display to the units specified in the pull down menu under "convert".
Dashboard was introduced in 2005 before advances in Internet security, and then participating websites later chose to close their site access to all but registered developers and/or pay for access business models. Many of the sites are gone, developers lost interest in supporting the third-party sites, and others like the weather widget had too many JavaScript dependencies to be maintainable, even if Yahoo! or the Weather Channel didn't change their site organization which broke the code. Apple had no control over the widget changes that used non-Apple sites.
So Dashboard was not a strategic product for Apple to maintain for a multitude of reasons in Catalina. As has been mentioned, there are compiled Today extensions that may replace some former Dashboard widgets, but certainly not all, and other lost Dashboard functionality will depend on your ability to adapt to change, and incorporate replacement solutions built into Catalina, or from the Mac App Store.
Catalina did a heinous deed in killing off Dashboard.
