Recently, the Nintendo Switch version of The Witcher 3: Wild Hunt was updated to include cross-save functionality with PC (via GOG and Steam). However, PlayStation players should not get their hopes up for The Witcher 3 cross-save to come to the PS4 or Xbox One, at least right now. A representative on behalf of developer CD Projekt RED confirmed that this feature was developed with Saber Interactive with the Switch in mind. It does not have cross-save in the works for any other platforms at this time.
Speaking with USgamer, the rep said:

PB = PB || {};
PB.gptStandAlone = PB.gptStandAlone || {};
PB.gptAutoRefresh = PB.gptAutoRefresh || {'gptAds':[], 'gptStandAlone':[]};
admiralCookie = readAdmiralCookie();
googletag.cmd.push(function() {
var standAloneSizeMapping = googletag.sizeMapping().addSize([0, 0], []).addSize([750, 0], [[300, 250]]).addSize([980, 0], [[300, 250]]).build(); PB.gptStandAlone['ros_300x250_p_slot4_1582124663'] = googletag.defineSlot('/4403/cr/playstationlifestyle/ros', [[300, 250]], 'ros_300x250_p_slot4_1582124663')
.defineSizeMapping(standAloneSizeMapping) .addService(googletag.pubads())
.setTargeting('pos', 'P').setTargeting('content_detail', '0').setTargeting('kw', 'in-article').setTargeting('coppa', '0').setTargeting('site', 'playstationlifestyle');
googletag.enableServices();
googletag.display('ros_300x250_p_slot4_1582124663');

if (admiralCookie === n...