In OH2 i had a HTTP set up to look at my weather station web page, then with a REGEX picking the data from the Weather station web page. I then had an item set up to show Temp and LUX.
I have rules working with these values to turn on lights when it gets dark.
Could be the same way. Depending on the HTTP binding you were using, if it was version 2 the same way would work. If you were using the (old) version 1 binding you need to change to the actual binding.
As said before the HTTP binding got updated to version 2, that way it could make the transition the OH3 ( all version 1 bindings can’t make that move).
Look into the documentation of the HTTP binding and make the move from within 2.5. After that you can make the move to OH3.