PLEXTOR Black 16X DVD+R 8X DVD+RW 6X DVD+R DL 16X DVD-R 4X DVD-RW 16X DVD- ROM 48X CD-R 24X CD-RW 48X CD-ROM 8M Cache IDE Slot Load DVD Burner - Newegg.com
Silverstone SST-SOD04 DVD-RW Slot-loading Slim Optical SATA Drive
External Slot loading slot-in CD DVD Drive USB 2.0 Type-C Slim Portable DVD +/-RW Writer Burner Rewriter For Apple Macbook Pro Laptop Desktop Accessories Win10 Win 8 compatible | Wish
Slot load DVD burner options for standard desktop case - Super User
Amazon.com: Slot Loading Portable External Blu-ray DVD Players, for Windows 10 2-in-1 15 17 Inch Touch Screen Laptop & Desktop Computer, Super Multi Blue-ray Player 8X DVD+-R DL CD-RW Burner Optical Drive
12.7mm Slot Load CD DVD DVDRW Optical Drive GA50N For De ll Alienware Notebook 15 17 18 M15x M17x M18x Series|optical drive|slot loadingdvd optical drive - AliExpress
Buy External Blu Ray DVD Drive KuWFi Player for Laptop USB3.0 Type-A & Type-C Dual interfaces Portable Slim Automatic Slot-Loading CDDVD-RAM Superdrive Burner with High Speed Data for PC Windows Mac OS
Panasonic UJ8C5A Slot-Loading DVD Burner
Here's something interesting: a slot-loading 5.25" optical drive made by GoldStar : r/vintagecomputing