I found myself in a similar position to you and went for used options. I had A mount lenses from previous cameras so stuck with A mount which is fine for my ability and the time I have to invest in photography. You can pick up an A77ii for reasonable money and then check out the lenses you want from a variety of sources/brands - I used Samyang/Sony/Minlota/Tamron - all amount. For wildlife I use a second hand Tamron 150-600mm zoom which is a fairly low cost entry.
You might find that whilst interchangeable lenses are great for learning on coupled with a couple of courses on using cameras in manual, you might end up reverting to using cameras just in auto
