Yes that is true. The M.2 slot is capable of a much higher data rate than a SATA port, so you can get drives that go in there which are much faster than SATA. No there is no workaround, that is a physical limitation.
You can also get M.2 drives which are slower or the same speed as SATA, and just use the M.2 slot for convenience and to keep costs down. Typically these use M-SATA as an interface whereas the blazing fast drives use NVMe, a different protocol on the same slot.
You don’t “need” an NVMe drive though. A 2.5in SATA SSD will be so much faster than your HDD it will blow you away. Something simple and cheap like a Samsung 870 EVO will be so much faster than any HDD and it operates totally silent as a little added bonus. Sequential read speeds on NVMe drives are flashy and the numbers are high, but it’s the instant seek times that really make the difference, and that’s the same on any SSD.
That said, if you did want an NVMe drive, there are options. For example the
SupaGeek M.2 SSD to PCIe Express 3.0 x4 Adapter Card
Is an excellent option for anyone without an M.2 slot and adds NVMe (but not M-SATA) to pretty much any PC with a Z97 chipset or better for just over a tenner.
The machine in my garage boots using one of these and is about 10 years old. Not every BIOS supports it, but everything I’ve tried it on has.