Me and my simple questions: Can I do this in FPGA?

Your friend doesnt know much. Altera provides floating point cores to do floating point arithmatic. https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/ug/ug_altfp_mfug.pdf

While you wouldnt be using much VHDL, you are designing a circuit. The VHDL would just glue the cores together.

But floating point in FPGA does have it's issues - it has high resource usage and high latency. If you have a constant data stream then the FPGA can process far more than a processor could handle (it can do it in real time - you basically build a custom co-processor). But if it's just a few calculations then it's probably easier to let an arm do the work.

So the answer is "Yes it can do it". But you will need to think seriously about how to implement it.