This is a weird opinion - Garmin is arguably the market leader, and they opened up all their formats and protocols to be standards which are now widely adopted (.fit files, ant+ wireless communication), and they also now work with the competing wireless communication standard too (btle).

And just looking at exercise bikes, it's true that peloton/flywheel/etc are closed. But the products in that space from the established fitness tech players (eg wahoo and tacx) are entirely based around communicating via standard protocols (ant+ fe-c trainer control).