@ Steven
Happy New Year !!!
RE: OSM does not have a routing feature. The only other option would be to generate a link to another routing provider which happens to use the OSM map tiles. I can not think of any of hand. Honestly, not sure it worth the effort. The button is simply a link to Google Maps with a latitude/longitude. No other information is passed and none is being queried from Google, at all.
Why not redirect the link to OSM, like this:
https://www.openstreetmap.org/#map=16/49.4414/6.0798
_https://www.openstreetmap.org/#map=[zoom]/[latitude]/[longitude]_
