Zero, zip, nada.
A right to repair law might mandate that any device with a battery also have the battery sold, by the manufacturer, for a reasonable period of time. That gives you a practical right to repair the device by replacing the battery, and it's well-defined.
"User replaceable" is not well defined. Does it mean you need to be able to do this with no tools at all? If not, what tools make it not 'user replaceable'? That no glue is used? Solder?
My watch is literally a cell phone, and I don't welcome law which might make it bulkier or more awkward, to mollify people who want a plastic hinge to pop out their smartphone battery and swap in a new one in the field.
The battery in my smartphone (and watch!) can be replaced by the manufacturer. Right-to-repair is about making sure that the owner of a device can do things themselves or from a third party, without licensing from the manufacturer: so selling consumable parts to all comers, providing some manuals maybe. It is not about whether you have the manual dexterity or special tooling to perform the replacement! If you want to optimize around that part being very easy, buy a product where it is, like the Dragonbox Pyra.