Finamp, very polished, actively developed and cross Platform. Requires a jellyfin instance. But thats a nice diy project in it self, can only recommend
IMHO there is no perfect solution for this, but I switched to Searxng (which can be selfhosted) and Im happy with the results. Please note that Searxng is a Meta Search engine, that basically means its using multiple other search engines with less tracking afaik...
Are the external USB drives using a external power cable or just USB power?
To me it sounds like you are hitting the Pis USB Power limit. You may want to get a cheap external USB dock with dedicated power supply