I would like to put family pictures on a memory stick and use that as my screensaver, is that something I can do?
If you have/create a Flickr account (https://www.flickr.com/), you can easily use the free Roku Developer "Photos" Channel (https://channelstore.roku.com/details/48b9b319192b3938cf0f619d45d0ff6d/photos).
You basically set Photos up as your Screensaver under Settings..Theme..Screensavers and then configure the Photo Channel to use the Flickr account with your own Photos. (set to private so no public viewing.)
If you have a USB Roku device like the Ultra, you can also try "Your Photos Screensaver" for 1.99 (https://channelstore.roku.com/details/ac497c4a0e18585f94195e4f3f1536ae/your-photos-screensaver)
There are probably other ways to accomplish same thing with other third party Channels/app on the Roku platform, but haven't experimented with them for a long while.
@renojim may hopefully have some suggestions as well for an easy method.
Edited: Also came across this method using Google Photoview that I was unaware of and may be the easiest method. (https://channelstore.roku.com/details/637cbf48183a52820a32e8a7a8ff865a/photoview-for-google-photos). Here is a tutorial for installing Google Photoview and using on RokuTV (as well as other smart OS systems) so similar procedure for attached Roku devices. (https://www.howtogeek.com/427448/how-to-make-your-tv-display-art-or-family-photos/)
Google Photoview link page/setup (https://www.photoviewapp.com/)