There are standard connectors for microphones, speakers, and headsets, but unfortunately the pinout diagram (schematic) changes very frequently. There is no guarantee that a headset with a 3.5mm TRRS plug that works with one radio will work with a radio from a different manufacturer, or even a different model radio of the same manufacturer. G4WPW's site tries to keep up with microphone connectors; have a look at it and you'll see the scope of the problem.
BTech has made things more complicated by defining yet another "standard"; even their brother company Baofeng seems to use a different pinout for the UV-3R PLUS.
Unfortunately, nobody seems to make a headset with a plug and pinout to match the UV-25X2, not even BTech, probably because not many people expect to plug headsets into mobile or base VHF/UHF rigs. People will likely want to use that same jack for APRS though.
Most speakers with a 3.5 mm plug (I assume that's a 3.5 mm jack) have the speaker connection on the tip, where the UV-25X2 has the PTT connection, so most commercially-available speakers won't work.
If you want to find a headset or speaker to work with your radio, you'll need to verify that the pinout diagram is correct by comparing its specifications to the pinout diagram from your manual. (Don't just take somebody's word for it from an internet review.) If there is no commercially-made speaker or headset that has the correct connector and pinout, then you have two remaining options: rewire the headset's or speaker's plug to work, or create some sort of adapter. If I had your problem I'd probably try to make a "pigtail" by connecting a 3.5 mm TRRS jack, wired for your chosen speaker or headset, to a 3.5 mm plug wired for your UV-25X2. Plugs and jacks that you can wire yourself with a soldering iron are available from several vendors, such as Jameco, Mouser, Digi-Key, and Newark.
