Yes, there are accessory rails available. Here are a few options:
https://www.opticsplanet.com/jp-rifles-tactical-rail-kit-accessories.html
JP actually makes a decent array of purpose made attachments, rails, and accessories that fit these rails including weights for precision shooting applications, sling swivels, and even Arca Swiss rails, just to name a few. Their pic rails arent the only way to attach gear. If you'd rather MLok, JP has a very similar handguard called the MK3 Standard (not the MK3 Rapid Configuration) Handguard that has long MLok Slots as opposed to lots of small MLok Slots like most aftermarket MLok handguards are designed. The reason for this is that there is less chance that you run into a positioning issue, being forced to mount an attachment in a certain place because that's where the MLok slot is. It also makes it easy to move an attachment without having to completely remove it from the guard and leap frog into the next open slot, but instead you barely loosen the attachment and just slide it down the long MLok channel to where you need it and a turn or two on the screws to tighten it back down. Pretty genius if you ask me. Hope this helped.