Am 24.03.21 schrieb me # home.com@3:770/3 in RBERRYPI:
FW> Is there a very simple interpreter for BASIC for BASH?
I haven't tried it myself, but there is a "bwBASIC" (Bywater BASIC) which is a small BASIC interpreter modeled after GW-BASIC. And there is FreeBASIC, which is more like QuickBASIC/QBASIC, but it is also a compiler.
Maybe that helps you a little.