Yes a thousand percent! I'm working on this too. I'm sick of everyone trying to come up with a use case to get all my data in everyone's cloud so I have to pay a subscription fee to just make things work. I'm working on a fitness tracking app right now that will use the sublime model - just buy it, get updates for X years, sync with all your devices and use it forever. If you want updates after X years buy the newest…
Bro who wants your pointless fitness data? Not even you care that much for that. Just use a notepad ffs.
A notepad also isn't enough to correlate heart rate etc to specific exercises and plotting over time