Quick answer
PayPal users can select any available funding source that is available in their PayPal account. This includes normal PayPal payments through a linked bank account, debit card or credit card, and also PayPal Credit and PayPal Pay in 4.
Reverb has no control or influence over the funding options that appear in your PayPal account when purchasing on Reverb. The funding options available to a PayPal user are determined by PayPal.
In addition to financing through PayPal Credit, many Reverb sellers accept Affirm Financing.