If you have a 2012 iMac then you already have a newer version of Bluetooth 4.0 (the current iMac’s offer 4.2) that as far as I know is fully compatible with everything being produced today. The newest version is called Bluetooth 5 and it is was just ratified and still very early for products.
While WiFi (802.11n) has been upgraded a few times current version (the current iMac offers 802.11ac) it would require more than the board to gain the higher throughput of the newest standards. MIMO requires more antenna’s than what your system has. The newest standard is WiFi 6 and it was just ratified and just being introduced
If you can’t directly wire your system to a hight speed Ethernet network directly you can still leverage it to connect to an external WiFi bridge which has the higher throughput WiFi (802.11ac)