(apologies; nothing to do with hiking routes, just me commenting on Discourse again)
You can certainly combine categories and tags - https://community.openstreetmap.org/tags/c/communities/pt/176/tomtom is an example of that,
https://meta.discourse.org/t/how-can-i-search-with-multiple-tags/27769/7 suggests that it should be possible to search for multiple tags (and and or), but the functionality is pretty well concealed 
Edit: The advanced search box is sometimes available, sometimes not, but a URL search as https://community.openstreetmap.org/search?q=tagging%20conditional%20tags%3Atagging%2Bconditional will search for two tags together. There’s no automatic link from there to “create a new post with these tags” (which there usually is for categories or just one tag), so the UI’s a bit rubbish though.