Definitely. Check out the Cap ‘n Ball channel. That guy rolls his own and has an extensive collection of 18th and 19th century rifles he does home made cartridges for.
One guy makes Chassepot cartridges, a bit involved. YT is erratic in enforcement of their anti-ammo/gun policies and a lot of black powder content is still up.
British Muzzleloaders is also a good bet to find hand made cartridges. The good news no one is as obnoxious as the guy in the OP.
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