MOST smart TVs will allow you to plug in a USB stick and watch videos or photos.
The same is true for most Blu-Ray players (including Sony and Oppo).
The apps they offer tend to be limited, and to only works with some formats and not others, but they do work.
Many vendors also have proprietary apps for "casting" videos and photos to your TV from a computer or phone.
There are also actually standards for sending audio and video from a computer to a TV - like "MiraCast".
The problem is that there are multiple standards - and various models and vendors may only support one or the other.
Unfortunately, this varies, and is continually changing, so you may need to do some research to find one that works with YOUR TV.
You will also find that each works with some videos and not others - depending on the format in which they were recorded.
MOST TVs and programs can display simple GIF pictures.
The bottom line is that you can probably find a cool one that works for your particular TV - but you might have to do some research to find it.
Of course, if you wish to create a more formal "slide show", with fancy transitions and captions, there are lots of programs for doing that...
Most then offer to output the resulting slide show as a video file which you can then play like any other video...
My 2017 Samsung TV can play a slide show of JPG images or a movie or video directly from a USB stick... and you can even set how long each picture remains onscreen and how they transition.
Samsung also has a neat little program for viewing or casting pictures and video from your computer or phone to your Samsung TV.
It's called Smart View and it's officially discontinued... but you can find it online if you do a search (it's free)
(You can either "send" a picture or movie to the TV, or access a file or folder on your computer FROM the TV.
It actually uses very little bandwidth since the TV actually decodes the video file... but it is limited to only certain video formats.)
However your Oppo player probably offers the most flexibility there - and also probably supports the widest variety of common picture and video types.