any plans about this feature development?

@maxdeepfield no plans, as far as I know.

I'd be happy to guide if someone would be willing to take this on.

I would like to see a method like that. It feels false to re-create a marker/line just because I want to change the behavior of the interactivity

I really need this functionality too, any updates or workarounds @perliedman?

Made this little function as a "plugin":

L.Layer.prototype.setInteractive = function (interactive) {
    if (this.getLayers) {
        this.getLayers().forEach(layer => {
            layer.setInteractive(interactive);
        });
        return;
    }
    if (!this._path) {
        return;
    }

    this.options.interactive = interactive;

    if (interactive) {
        L.DomUtil.addClass(this._path, 'leaflet-interactive');
    } else {
        L.DomUtil.removeClass(this._path, 'leaflet-interactive');
    }
};

Just call it like every other function e.g. layer.setInteractive(true) or layerGroup.setInteractive(false).

Thanks @Jadaw1n ! That worked like a charm, here it is in Typescript for anyone who wants it:

export class InteractiveImageOverlay extends L.ImageOverlay {
    setInteractive(interactive: boolean) {
        this.options.interactive = interactive;

        if (interactive) {
            L.DomUtil.addClass(this.getElement(), 'leaflet-interactive');
            this._map.on('click', (event: L.LeafletMouseEvent) => {
                this.fireEvent('click', event);
            });
        } else {
            L.DomUtil.removeClass(this.getElement(), 'leaflet-interactive');
            this._map.removeEventListener('click');
        }
    }
}

@Jadaw1n it is a nice solution you've shared, unfortunately for me it doesn't work with canvas elements

@Jadaw1n Wanted to say thanks for your code. I ran into this issue changing my rendering from canvas to SVG. Surprised this isn't in leaflet by now.