I checked Velobase and the Rd is the Shimano RD AL11 and the FD is the FD AL11 and per Velobase they are both friction shifting. I thought all Rd's with a barrel adjuster were index shifting and "assumed" that with thumb shifters it would have to be an indexing system.
Assuming my guess was off or will these derailleurs work in index anyway????
I'm pretty sure the derailleurs will not index, but you can still use bar-end shifters in friction mode.
Brifters are not going to work, but If you do want to go with a drop bar set-up, you could acquire a pair of Gevenalle Audax or CX brake levers with shifters.
https://www.gevenalle.com/product/audax/
https://www.gevenalle.com/product/cx2/