DrJeff
1. Roku in and of itself has no DVR capabilties, but the channels/apps that you subscribe to may have DVR capabilities. Roku will work on Google fiber.
2. While you can certainly subscribe to Hallmark Plus https://channelstore.roku.com/details/f51ec27fd29492c1fa58fe9afd7a73e9/hallmark for your Roku device, https://www.hallmarkplus.com/, you may find a better deal using FrndlyTV that carries Hallmark Channel, Hallmark Mysteries, Hallmark Family and is running a current special to include Hallmark Plus. Frndly includes an unlimited DVR service. https://try.frndlytv.com/
The free Roku Channel also has a Hallmark Channel Live TV linear channel that shows Hallmark movies (Hallmark Movies and More). This is different from what you see on Frndly or other subscription channels but is 24/7. Other free channels/apps on the Roku platform also run this same Hallmark Live TV channel. You can get a feel for it from the online Roku Channel. https://therokuchannel.roku.com/watch/08973e5adc625d15aaa9c4c13cfb0307/hallmark-movies-and-more