On Mon, 26 Mar 2018 21:17:39 -0400, Keith Nuttle
said:

Does your TV have a USB port?

No. The router has a USB port.
The Playstation 3 has USB ports.
The Windows 10 desktop computer has USB ports.

The TV is just these ports which are not USB or HDMI.
http://www.bild.me/bild.php?file=7549633sony_cables.jpg

The TV is just connected to the PlayStation 3 and DVD player.

The only device with HDMI is the one desktop computer and monitor.

I'm on WISP. About 5 Mbps down and up.
The router is an old WNDR Netgear N with the USB port unused.
I am a novice to smart TV, but from what I have read 5 Mbps is about the
minimum for low resolution moves, but that would probably be acceptable
for TV shows.

We had a friend over who used her Netflix account somehow on the
PlayStation 3 to play to the Sony TV where the Playstation 3 is connected
to the router by wire, so the TV has Internet only that way (through the
PS3).

The TV is a very old model.
http://www.bild.me/bild.php?file=6286595sony_model.jpg

The Internet comes in to the WISP modem and then goes to the router and
then goes to the PS3 and then to the TV.

If you can get Netflix through the play station, you may be able to
access the net and get to the several free, or nominal cost sites.

That is the kind of advice I was hoping to get!
It didn't even occur to me that the PS3 had HDMI!

I just looked, and the PS3 does have an unused HDMI port!
http://www.bild.me/bild.php?file=6417873ps3.jpg

I don't know about your area but I have found there are quite a lot of
material available on the local Public TV website.

I was hoping that the Roku "came with" some free channels.
We don't have any right now, so anything is better than nothing.

As for Broadcast TV, you may wish to check this site:
https://www.fcc.gov/media/engineering/dtvmaps
This will give you an idea of the station available in your area. Many
broadcast TV station have one primary and several secondary channels. I
consider them point channels as the are 5.0, 5.2; 17.1, 17.2, 17.3,
17.4; etc. In my area there are five primary channel, and with the
secondary channel there are a total of about 16 channels to choose from.

You may also consider and amplified antenna. Use the information from
the above site to determine the amplification you need for your area.

We don't really need TV, so we don't want to go the "broadcast" TV method
which will require an antenna from the roof to the bottom floor which is
just too much work, really, for crummy channels.

What you told me that I didn't know is that the PS3 has that unused HDMI
port!

Can the Roku be connected to that PS3?