I bought this https://www.amazon.com/dp/B07LBK6Y1J/ref=cm_sw_r_cp_apa_glt_fabc_JW787XN22P4VERBDSZB7?_encoding=UTF8&psc=1
It's an fm modulator and works great plus gives me hands free for phone. Every now and then I get engine whine (you can't hear when music is playing) but reseating the adapter fixes it.
Honestly, I don't care for the Bose speakers. Their range is terrible. My generic run off the mill factory setup in my Ford escape sounds million times better.
This is the one I use, it plugs into the cigarette port since my car is a 2005 Ford Focus and has no bluetooth or aux.
Another question: If I buy an FM transmitter such as this one, would I be able to hook it up to the car?
You need to define 'best'
Cheap
Get a Bluetooth FM transmitter. Plugs into cigarette lighter, connects to your phone via bluetooth and broadcasts FM signal you tune the radio to.
Gucci
Get a bracket like this if you don't have climate control there's a different one.
Then your choice of any Double DIN head unit, features go way up but BT is usually standard. I'd go with Android auto tbh.
My car doesn't have a headphone/aux port either but I bought this on Amazon and it works really well FWIW
Nulaxy Bluetooth FM Transmitter... https://www.amazon.com/dp/B07LBK6Y1J?ref=ppx_pop_mob_ap_share
Nulaxy Bluetooth FM Transmitter for Car, 7 Color LED Backlit Bluetooth Car Adapter with QC3.0 Charging, Support Siri Google Assistant, USB Flash Drive, microSD Card, Handsfree Car Kit - NX09 Silver https://www.amazon.com/dp/B07LBK6Y1J/ref=cm_sw_r_cp_apa_i_pgAyDbD8J7322