The Microchip SNAP programmer/debugging tool is on sale for 50% off, making it by far the cheapest official debugger/programmer for Arduino-class chips.
It does ISP and DW (Atmega328p ATtiny85, etc), UPDI (new Mega0 and xTiny chips, like the ATmega4809), SWD (Atmel ARM chips), and JTAG (other ARM chips), as well as the protocols used for many of the PIC chips (8, 16, and 32bits) that “we” don’t use much.
(However, it does not support any High Voltage Programming. At least, not on its own.)
at less than $8, it’s a good deal!