This needs to be implemented in order for something like this to become possible: https://feedback.telerik.com/blazor/1422740-conditional-command-buttons-shown-on-condition-based-on-model-values-and-or-invoking-cud-operations-programmatically.
I must also note that at this point I can't say whether it will suffice, though. There is a general problem with the InCell and InLine edit modes - we don't have the cells to put our editors in, so we could not possibly do that. Perhaps the PopUp mode would work, though, it's early to say. Generally, when using a row template, one needs to implement all features the grid offers there. For example, use a generic button that toggles a flag in the model and shows a second set of markup instead - that allows editing.
UI for Blazor