Oberon is even older than Delphi; a more modern version is Oberon+: https://oberon-lang.github.io/

Is this still actively developed?

Yes, see e.g. https://github.com/rochus-keller/Oberon/

It was great for its time, nowadays we would be better off having a similar experience based on Go, C#, D,...

Add Vlang in there too, which inherited the Oberon-2 method syntax and has Pascal/Wirthian influence.

The original is much less jumbled.

Here is the language specification:

https://miasap.se/obnc/oberon-report.html

I would recommend everyone to learn Oberon just to see how concisely defined an imperative, structured, procedural and modular language with support for object oriented programming (extended types) can be. The language reference is only around 16 pages long including examples and formal grammar.