The effective throughput of Bluetooth 5.0, is ~1.6 Megabits/second with a good signal (actual speed is 2.0 Megabits/second, but a fair amount is consumed with transmission overhead).
With that said, the keyboard and mouse definitely do not use a lot of data bandwidth. Depending on how your heart rate monitor is reporting data, that can be low to medium low bandwidth. Your interactive trainer also depends on how much data and how often it is reported. Then there is the audio. How much bandwidth it consumes totally depends on the quality that is being sent and if it is using Bluetooth compression or data passthrough, like AAC. normal iTunes downloads are 256 kilobit/sec streams. Also, the audio receiving device will also dictate what can be sent.
So, with that said, it is a matter of adding up the numbers to see if it is feasible and the easiest way is to just try and see what happens.